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Ataga KI, Kutlar A, Kanter J, Liles D, Cancado R, Friedrisch J, Guthrie TH, Knight-Madden J, Alvarez OA, Gordeuk VR, Gualandro S, Colella MP, Smith WR, Rollins SA, Stocker JW, Rother RP. Crizanlizumab for the Prevention of Pain Crises in Sickle Cell Disease. N Engl J Med 2017; 376:429-439. [PMID: 27959701 PMCID: PMC5481200 DOI: 10.1056/nejmoa1611770] [Citation(s) in RCA: 508] [Impact Index Per Article: 72.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND The up-regulation of P-selectin in endothelial cells and platelets contributes to the cell-cell interactions that are involved in the pathogenesis of vaso-occlusion and sickle cell-related pain crises. The safety and efficacy of crizanlizumab, an antibody against the adhesion molecule P-selectin, were evaluated in patients with sickle cell disease. METHODS In this double-blind, randomized, placebo-controlled, phase 2 trial, we assigned patients to receive low-dose crizanlizumab (2.5 mg per kilogram of body weight), high-dose crizanlizumab (5.0 mg per kilogram), or placebo, administered intravenously 14 times over a period of 52 weeks. Patients who were receiving concomitant hydroxyurea as well as those not receiving hydroxyurea were included in the study. The primary end point was the annual rate of sickle cell-related pain crises with high-dose crizanlizumab versus placebo. The annual rate of days hospitalized, the times to first and second crises, annual rates of uncomplicated crises (defined as crises other than the acute chest syndrome, hepatic sequestration, splenic sequestration, or priapism) and the acute chest syndrome, and patient-reported outcomes were also assessed. RESULTS A total of 198 patients underwent randomization at 60 sites. The median rate of crises per year was 1.63 with high-dose crizanlizumab versus 2.98 with placebo (indicating a 45.3% lower rate with high-dose crizanlizumab, P=0.01). The median time to the first crisis was significantly longer with high-dose crizanlizumab than with placebo (4.07 vs. 1.38 months, P=0.001), as was the median time to the second crisis (10.32 vs. 5.09 months, P=0.02). The median rate of uncomplicated crises per year was 1.08 with high-dose crizanlizumab, as compared with 2.91 with placebo (indicating a 62.9% lower rate with high-dose crizanlizumab, P=0.02). Adverse events that occurred in 10% or more of the patients in either active-treatment group and at a frequency that was at least twice as high as that in the placebo group were arthralgia, diarrhea, pruritus, vomiting, and chest pain. CONCLUSIONS In patients with sickle cell disease, crizanlizumab therapy resulted in a significantly lower rate of sickle cell-related pain crises than placebo and was associated with a low incidence of adverse events. (Funded by Selexys Pharmaceuticals and others; SUSTAIN ClinicalTrials.gov number, NCT01895361 .).
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Affiliation(s)
- Kenneth I Ataga
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Abdullah Kutlar
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Julie Kanter
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Darla Liles
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Rodolfo Cancado
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - João Friedrisch
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Troy H Guthrie
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Jennifer Knight-Madden
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Ofelia A Alvarez
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Victor R Gordeuk
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Sandra Gualandro
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Marina P Colella
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Wally R Smith
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Scott A Rollins
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Jonathan W Stocker
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
| | - Russell P Rother
- From the Division of Hematology-Oncology, University of North Carolina, Chapel Hill (K.I.A.), and the Division of Hematology-Oncology, East Carolina University, Greenville (D.L.) - both in North Carolina; the Sickle Cell Center, Medical College of Georgia, Augusta University, Augusta (A.K.); the Division of Pediatrics, Medical University of South Carolina, Charleston (J.K.); the Department of Hematology-Oncology, Santa Casa Medical School of São Paulo (R.C.), and the Division of Hematology, University of São Paulo (S.G.), São Paulo, the Hematology and Bone Marrow Transplantation Service, Hospital de Clínicas de Porto Alegre, Porto Alegre (J.F.), and the Hematology and Hemotherapy Center, University of Campinas, Campinas (M.P.C.) - all in Brazil; the Baptist Cancer Institute, Baptist Medical Center, Jacksonville, FL (T.H.G.); the Sickle Cell Unit, University of the West Indies, Mona, Jamaica (J.K.-M.); the Division of Pediatric Hematology-Oncology, University of Miami, Miami (O.A.A.); the Department of Medicine, University of Illinois at Chicago, Chicago (V.R.G.); the Division of General Internal Medicine, Virginia Commonwealth University Medical Center, Richmond (W.R.S.); and Selexys Pharmaceuticals, Oklahoma City (S.A.R., J.W.S., R.P.R.)
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Rother RP, Rollins SA, Mojcik CF, Brodsky RA, Bell L. Discovery and development of the complement inhibitor eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria. Nat Biotechnol 2008; 25:1256-64. [PMID: 17989688 DOI: 10.1038/nbt1344] [Citation(s) in RCA: 528] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The complement system provides critical immunoprotective and immunoregulatory functions but uncontrolled complement activation can lead to severe pathology. In the rare hemolytic disease paroxysmal nocturnal hemoglobinuria (PNH), somatic mutations result in a deficiency of glycosylphosphatidylinositol-linked surface proteins, including the terminal complement inhibitor CD59, on hematopoietic stem cells. In a dysfunctional bone marrow background, these mutated progenitor blood cells expand and populate the periphery. Deficiency of CD59 on PNH red blood cells results in chronic complement-mediated intravascular hemolysis, a process central to the morbidity and mortality of PNH. A recently developed, humanized monoclonal antibody directed against complement component C5, eculizumab (Soliris; Alexion Pharmaceuticals Inc., Cheshire, CT, USA), blocks the proinflammatory and cytolytic effects of terminal complement activation. The recent approval of eculizumab as a first-in-class complement inhibitor for the treatment of PNH validates the concept of complement inhibition as an effective therapy and provides rationale for investigation of other indications in which complement plays a role.
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Affiliation(s)
- Russell P Rother
- Alexion Pharmaceuticals, Inc., 352 Knotter Drive, Cheshire, Connecticut 06410, USA.
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Hillmen P, Muus P, Dührsen U, Risitano AM, Schubert J, Luzzatto L, Schrezenmeier H, Szer J, Brodsky RA, Hill A, Socié G, Bessler M, Rollins SA, Bell L, Rother RP, Young NS. Effect of the complement inhibitor eculizumab on thromboembolism in patients with paroxysmal nocturnal hemoglobinuria. Blood 2007; 110:4123-8. [PMID: 17702897 DOI: 10.1182/blood-2007-06-095646] [Citation(s) in RCA: 367] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Hemolysis and hemoglobinemia contribute to serious clinical sequelae in hemolytic disorders. In paroxysmal nocturnal hemoglobinuria (PNH) patients, hemolysis can contribute to thromboembolism (TE), the most feared complication in PNH, and the leading cause of disease-related deaths. We evaluated whether long-term treatment with the complement inhibitor eculizumab reduces the rate of TE in patients with PNH. Clinical trial participants included all patients in the 3 eculizumab PNH clinical studies, which recruited patients between 2002 and 2005 (n = 195); patients from these studies continued treatment in the current multinational open-label extension study. Thromboembolism rate with eculizumab treatment was compared with the pretreatment rate in the same patients. The TE event rate with eculizumab treatment was 1.07 events/100 patient-years compared with 7.37 events/100 patient-years (P < .001) prior to eculizumab treatment (relative reduction, 85%; absolute reduction, 6.3 TE events/100 patient-years). With equalization of the duration of exposure before and during treatment for each patient, TE events were reduced from 39 events before eculizumab to 3 events during eculizumab (P < .001). The TE event rate in antithrombotic-treated patients (n = 103) was reduced from 10.61 to 0.62 events/100 patient-years with eculizumab treatment (P < .001). These results show that eculizumab treatment reduces the risk of clinical thromboembolism in patients with PNH. This study is registered at http://clinicaltrials.gov (study ID no. NCT00122317).
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Hillmen P, Young NS, Schubert J, Brodsky RA, Socié G, Muus P, Röth A, Szer J, Elebute MO, Nakamura R, Browne P, Risitano AM, Hill A, Schrezenmeier H, Fu CL, Maciejewski J, Rollins SA, Mojcik CF, Rother RP, Luzzatto L. The complement inhibitor eculizumab in paroxysmal nocturnal hemoglobinuria. N Engl J Med 2006; 355:1233-43. [PMID: 16990386 DOI: 10.1056/nejmoa061648] [Citation(s) in RCA: 811] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND We tested the safety and efficacy of eculizumab, a humanized monoclonal antibody against terminal complement protein C5 that inhibits terminal complement activation, in patients with paroxysmal nocturnal hemoglobinuria (PNH). METHODS We conducted a double-blind, randomized, placebo-controlled, multicenter, phase 3 trial. Patients received either placebo or eculizumab intravenously; eculizumab was given at a dose of 600 mg weekly for 4 weeks, followed 1 week later by a 900-mg dose and then 900 mg every other week through week 26. The two primary end points were the stabilization of hemoglobin levels and the number of units of packed red cells transfused. Biochemical indicators of intravascular hemolysis and the patients' quality of life were also assessed. RESULTS Eighty-seven patients underwent randomization. Stabilization of hemoglobin levels in the absence of transfusions was achieved in 49% (21 of 43) of the patients assigned to eculizumab and none (0 of 44) of those assigned to placebo (P<0.001). During the study, a median of 0 units of packed red cells was administered in the eculizumab group, as compared with 10 units in the placebo group (P<0.001). Eculizumab reduced intravascular hemolysis, as shown by the 85.8% lower median area under the curve for lactate dehydrogenase plotted against time (in days) in the eculizumab group, as compared with the placebo group (58,587 vs. 411,822 U per liter; P<0.001). Clinically significant improvements were also found in the quality of life, as measured by scores on the Functional Assessment of Chronic Illness Therapy-Fatigue instrument (P<0.001) and the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire. Of the 87 patients, 4 in the eculizumab group and 9 in the placebo group had serious adverse events, none of which were considered to be treatment-related; all these patients recovered without sequelae. CONCLUSIONS Eculizumab is an effective therapy for PNH.
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Rinder CS, Rinder HM, Smith MJ, Fitch JCK, Tracey JB, Chandler WL, Rollins SA, Smith BR. Antithrombin reduces monocyte and neutrophil CD11b up regulation in addition to blocking platelet activation during extracorporeal circulation. Transfusion 2006; 46:1130-7. [PMID: 16836559 DOI: 10.1111/j.1537-2995.2006.00861.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Patients undergoing cardiac surgery requiring cardiopulmonary bypass develop a systemic inflammatory reaction. Antithrombin III (AT) has anticoagulant effects but also shows evidence of anti-inflammatory activity. The aim of this study was to examine whether exogenous AT could reduce white blood cell activation (CD11b up regulation or elastase release), in addition to inhibiting platelet (PLT) activation and fibrin generation, during simulated cardiopulmonary bypass (sCPB), undertaken in the absence of endothelium. STUDY DESIGN AND METHODS sCPB was carried out with minimally heparinized (2 U/mL) human blood for 90 minutes in controls and with supplementation by low-dose (1 U/mL) and high-dose (5 U/mL) AT. RESULTS High-dose AT blunted thrombin generation during sCPB (prothrombin fragment 1.2); both doses significantly inhibited thrombin activity (fibrinopeptide A). Complement activation (C3a and C5b-9) was unaffected by AT. High-dose AT inhibited PLT activation (P-selectin expression and P-selectin-dependent monocyte-PLT conjugate formation). AT supplementation at the higher dose significantly abrogated monocyte and neutrophil CD11b up regulation and neutrophil elastase release. CONCLUSION In addition to anticoagulant and anti-PLT effects, pharmacologic AT doses significantly blunted monocyte and neutrophil CD11b up regulation and neutrophil elastase release during sCPB, independent of endothelial effects. These data provide evidence for the direct anti-inflammatory activity of AT that has clinical relevance for CPB complications.
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Affiliation(s)
- Christine S Rinder
- Department of Anesthesiology, Yale University School of Medicine, New Haven, Connecticut 06520-8051, USA.
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6
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Chen JC, Rollins SA, Shernan SK, Boyce S, Allen K, Wallace A, Malloy KJ, Eng JS, Colman RW, Fitch JCK. Pharmacologic C5-complement suppression reduces blood loss during on-pump cardiac surgery. J Card Surg 2005; 20:35-41. [PMID: 15673408 DOI: 10.1111/j.0886-0440.2005.200370.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Inflammation contributes to morbidity following on-pump cardiac surgery. Complement activation during cardiopulmonary bypass has been associated with the postoperative bleeding and tissue injury. This study examines the pharmacology and impact on blood loss of complement C5 suppression with pexelizumab in patients undergoing cardiac surgery with cardiopulmonary bypass. METHODS Pexelizumab, a humanized monoclonal antibody single-chain fragment that binds to the human C5 complement component, was studied in a Phase II multicentered clinical trial. CABG (n = 800) and CABG with concomitant valve surgery (n = 114) patients were evaluated. Patients were randomized to either: pexelizumab bolus (2.0 mg/kg) + placebo infusion; pexelizumab bolus (2.0 mg/kg) + pexelizumab infusion (0.05 mg/kg/hour for 24 hours); or placebo bolus + placebo infusion. Pharmacology, chest tube drainage, and transfusion requirements were assessed. RESULTS Mean maximum pexelizumab serum concentration was similar for bolus and bolus + infusion-treated patients. Complement-dependent serum hemolytic activity was completely suppressed within 1 hour following pexelizumab bolus, however, suppression was maintained for a longer duration in the bolus + infusion compared to the bolus-only treated patients. A reduction in chest tube drainage was observed for all pexelizumab-treated patients, although transfusion of blood products was similar across all study groups. CONCLUSION Pexelizumab administration inhibits complement-dependent hemolytic activity and is associated with a reduction in postoperative chest tube drainage in patients undergoing cardiac surgery requiring cardiopulmonary bypass. Further, clinical studies are needed to assess the value of complement attenuation in this setting.
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Affiliation(s)
- John C Chen
- Division of Cardiothoracic Surgery, University of Hawaii School of Medicine, Department of Anatomy and Physiology, University of Hawaii, 3288 Moanalua Road, Honolulu, HI 96819, USA.
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7
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Verrier ED, Shernan SK, Taylor KM, Van de Werf F, Newman MF, Chen JC, Carrier M, Haverich A, Malloy KJ, Adams PX, Todaro TG, Mojcik CF, Rollins SA, Levy JH. Terminal complement blockade with pexelizumab during coronary artery bypass graft surgery requiring cardiopulmonary bypass: a randomized trial. JAMA 2004; 291:2319-27. [PMID: 15150203 DOI: 10.1001/jama.291.19.2319] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Inflammation and ischemia-reperfusion injury during coronary artery bypass graft (CABG) surgery requiring cardiopulmonary bypass are associated with postoperative myocardial infarction (MI) and mortality. OBJECTIVE To determine the efficacy and safety of pexelizumab, a C5 complement inhibitor, in reducing perioperative MI and mortality in CABG surgery. DESIGN, SETTING, AND PARTICIPANTS A randomized, double-blind, placebo-controlled trial, including 3099 patients (> or = 18 years) undergoing CABG surgery with or without valve surgery at 205 hospitals in North America and Western Europe from January 2002 to February 2003. INTERVENTIONS Patients were randomly assigned to receive intravenous pexelizumab (2.0 mg/kg bolus plus 0.05 mg/kg per hour for 24 hours; n = 1553) or placebo (n = 1546) 10 minutes before undergoing the procedure. MAIN OUTCOME MEASURES The primary composite end point was the incidence of death or MI within 30 days of randomization in those undergoing CABG surgery only (n = 2746). Secondary analyses included the intent-to-treat analyses of death or MI composite at days 4 and 30 in all 3099 study patients. RESULTS After 30 days, 134 (9.8%) of 1373 of patients receiving pexelizumab vs 161 (11.8%) of 1359 of patients receiving placebo (relative risk, 0.82; 95% confidence interval, 0.66-1.02; P =.07) died or experienced MI in the CABG surgery only population. In the intent-to-treat analyses, 178 (11.5%) of 1547 patients receiving pexelizumab vs 215 (14.0%) of 1535 receiving placebo died or experienced MI (relative risk, 0.82; 95% confidence interval, 0.68-0.99; P =.03). The trial was not powered to detect a reduction in mortality alone. CONCLUSIONS Compared with placebo, pexelizumab was not associated with a significant reduction in the risk of the composite end point of death or MI in 2746 patients who had undergone CABG surgery only but was associated with a statistically significant risk reduction 30 days after the procedure among all 3099 patients undergoing CABG with or without valve surgery.
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Affiliation(s)
- Edward D Verrier
- Division of Cardiothoracic Surgery, University of Washington School of Medicine, Seattle 98195-6310, USA.
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8
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Shernan SK, Fitch JCK, Nussmeier NA, Chen JC, Rollins SA, Mojcik CF, Malloy KJ, Todaro TG, Filloon T, Boyce SW, Gangahar DM, Goldberg M, Saidman LJ, Mangano DT. Impact of pexelizumab, an anti-C5 complement antibody, on total mortality and adverse cardiovascular outcomes in cardiac surgical patients undergoing cardiopulmonary bypass. Ann Thorac Surg 2004; 77:942-9; discussion 949-50. [PMID: 14992903 DOI: 10.1016/j.athoracsur.2003.08.054] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/19/2003] [Indexed: 12/26/2022]
Abstract
BACKGROUND During cardiac surgery requiring cardiopulmonary bypass, pro-inflammatory complement pathways are activated by exposure of blood to bio-incompatible surfaces of the extracorporeal circuit and reperfusion of ischemic organs. Complement activation promotes the generation of additional inflammatory mediators thereby exacerbating tissue injury. We examined the safety and efficacy of a C5 complement inhibitor for attenuating inflammation-mediated cardiovascular dysfunction in cardiac surgical patients undergoing cardiopulmonary bypass. METHODS Pexelizumab (Alexion Pharmaceuticals, Inc, Cheshire, CT), a recombinant, single-chain, anti-C5 monoclonal antibody, was evaluated in a randomized, double-blinded, placebo-controlled, multicenter trial that involved 914 patients undergoing coronary artery bypass grafting with or without valve surgery requiring cardiopulmonary bypass. RESULTS Pexelizumab was administered intravenously as a bolus (2.0 mg/kg) or bolus plus infusion (2.0 mg/kg plus 0.05 mg/kg/h for 24 hours), and inhibited complement activation. There were no statistically significant differences between placebo-treated and pexelizumab-treated patients in the primary endpoint (composite of death, or new Q-wave, or non-Q-wave [myocardial-specific isoform of creatine kinase > 60 ng/mL] myocardial infarction, or left ventricular dysfunction, or new central nervous system deficit). However, post hoc analysis revealed a reduction in the composite of death or myocardial infarction (myocardial-specific isoform of creatine kinase >/= 100 ng/mL) for the isolated coronary artery bypass grafting, bolus plus infusion subgroup on POD 4 (p = 0.007) and on POD 30 (p = 0.004). CONCLUSIONS Pexelizumab had no statistically significant effect on the primary endpoint. However, the reduction in death or myocardial infarction (myocardial-specific isoform of creatine kinase >/= 100 ng/mL) as revealed in the post hoc analysis in the isolated coronary artery bypass grafting bolus plus infusion subpopulation, suggests that further investigation of anti-C5 therapy for ameliorating complement-mediated inflammation and myocardial injury is warranted.
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Affiliation(s)
- Stanton K Shernan
- Division of Cardiothoracic Surgery, University of Hawaii School of Medicine, Honolulu, Hawaii, USA.
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9
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Hillmen P, Hall C, Marsh JCW, Elebute M, Bombara MP, Petro BE, Cullen MJ, Richards SJ, Rollins SA, Mojcik CF, Rother RP. Effect of eculizumab on hemolysis and transfusion requirements in patients with paroxysmal nocturnal hemoglobinuria. N Engl J Med 2004; 350:552-9. [PMID: 14762182 DOI: 10.1056/nejmoa031688] [Citation(s) in RCA: 422] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Paroxysmal nocturnal hemoglobinuria (PNH) arises from a somatic mutation of the PIG-A gene in a hematopoietic stem cell and the subsequent production of blood cells with a deficiency of surface proteins that protect the cells against attack by the complement system. We tested the clinical efficacy of eculizumab, a humanized antibody that inhibits the activation of terminal complement components, in patients with PNH. METHODS Eleven transfusion-dependent patients with PNH received infusions of eculizumab (600 mg) every week for four weeks, followed one week later by a 900-mg dose and then by 900 mg every other week through week 12. Clinical and biochemical indicators of hemolysis were measured throughout the trial. RESULTS Mean lactate dehydrogenase levels decreased from 3111 IU per liter before treatment to 594 IU per liter during treatment (P=0.002). The mean percentage of PNH type III erythrocytes increased from 36.7 percent of the total erythrocyte population to 59.2 percent (P=0.005). The mean and median transfusion rates decreased from 2.1 and 1.8 units per patient per month to 0.6 and 0.0 units per patient per month, respectively (P=0.003 for the comparison of the median rates). Episodes of hemoglobinuria were reduced by 96 percent (P<0.001), and measurements of the quality of life improved significantly. CONCLUSIONS Eculizumab is safe and well tolerated in patients with PNH. This antibody against terminal complement protein C5 reduces intravascular hemolysis, hemoglobinuria, and the need for transfusion, with an associated improvement in the quality of life in patients with PNH.
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Affiliation(s)
- Peter Hillmen
- Department of Haematology, Leeds Teaching Hospitals National Health Science Trust, Leeds, United Kingdom.
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10
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Clark DJ, Cleman MW, Pfau SE, Rollins SA, Ramahi TM, Mayer C, Caulin-Glaser T, Daher E, Kosiborod M, Bell L, Setaro JF. Serum complement activation in congestive heart failure. Am Heart J 2001; 141:684-90. [PMID: 11275938 DOI: 10.1067/mhj.2001.113758] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Although activation of the complement system in myocardial infarction and cardiopulmonary bypass has been shown to contribute to myocardial injury, its role in congestive heart failure (CHF) is unknown. The purpose of this study was to determine the presence of terminal complement activation and its relation to clinical outcomes in patients with CHF. METHODS We measured serum levels of the terminal complement complex C5b-9 in 36 patients with symptomatic heart failure and left ventricular ejection fraction <40%. We compared the serum C5b-9 levels of these patients with CHF with a group of 12 age-matched control patients. Combined clinical outcomes (death, urgent heart transplantation, or hospitalization with worsening heart failure) at 6 months were determined. RESULTS The serum C5b-9 [median (25th to 75th percentiles)] levels in 36 patients with CHF [101.5 ng/mL (40 to 164)] were significantly (P =.003) higher than in the 12 control patients [36.5 ng/mL (22 to 50)]. Significantly more of the patients with CHF with the highest levels of C5b-9 (highest 50th percentile) had New York Heart Association class IV symptoms (67% vs 33%; P =.04) and adverse clinical outcomes by 6 months (56% vs 17%; P =.02) compared with the patients with CHF with lower levels (lowest 50th percentile). CONCLUSIONS We have described a significant elevation in circulating C5b-9, the terminal complement complex, in patients with symptomatic heart failure and have observed an association between high levels of C5b-9 and near-term adverse events.
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Affiliation(s)
- D J Clark
- Section of Cardiovascular Medicine, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520, USA
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11
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Collard CD, Väkevä A, Morrissey MA, Agah A, Rollins SA, Reenstra WR, Buras JA, Meri S, Stahl GL. Complement activation after oxidative stress: role of the lectin complement pathway. Am J Pathol 2000; 156:1549-56. [PMID: 10793066 PMCID: PMC1876913 DOI: 10.1016/s0002-9440(10)65026-2] [Citation(s) in RCA: 256] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The complement system plays an important role in mediating tissue injury after oxidative stress. The role of mannose-binding lectin (MBL) and the lectin complement pathway (LCP) in mediating complement activation after endothelial oxidative stress was investigated. iC3b deposition on hypoxic (24 hours; 1% O(2))/reoxygenated (3 hours; 21% O(2)) human endothelial cells was attenuated by N-acetyl-D-glucosamine or D-mannose, but not L-mannose, in a dose-dependent manner. Endothelial iC3b deposition after oxidative stress was also attenuated in MBL-deficient serum. Novel, functionally inhibitory, anti-human MBL monoclonal antibodies attenuated MBL-dependent C3 deposition on mannan-coated plates in a dose-dependent manner. Treatment of human serum with anti-MBL monoclonal antibodies inhibited MBL and C3 deposition after endothelial oxidative stress. Consistent with our in vitro findings, C3 and MBL immunostaining throughout the ischemic area at risk increased during rat myocardial reperfusion in vivo. These data suggest that the LCP mediates complement activation after tissue oxidative stress. Inhibition of MBL may represent a novel therapeutic strategy for ischemia/reperfusion injury and other complement-mediated disease states.
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Affiliation(s)
- C D Collard
- Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA
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12
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Rollins SA, Johnson KK, Li L, Birks C, Matis LA, Rother RP. Role of porcine P-selectin in complement-dependent adhesion of human leukocytes to porcine endothelial cells. Transplantation 2000; 69:1659-67. [PMID: 10836378 DOI: 10.1097/00007890-200004270-00023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Rapid leukocyte adherence to donor organ vasculature is a hallmark of hyperacute xenograft rejection. However, the molecular interactions required for leukocyte binding to vascular endothelium have not been characterized. METHODS AND RESULTS Binding assays performed between human neutrophils and porcine aortic endothelial cells (PAEC) after exposure to human complement demonstrated that adhesion was mediated by both surface-bound C3b and C5b-9 activity. C5b-9-dependent adhesion was blocked by neuraminidase treatment of the neutrophils, suggesting that this binding was mediated by porcine P-selectin. Porcine P-selectin was isolated from a PAEC cDNA library. The porcine P-selectin primary sequence contained an open reading frame encoding 646 amino acids with 82% identity to human P-selectin. Recombinant soluble porcine P-selectin specifically bound to human neutrophils and HL-60 cells. Transfection of COS cells with the full-length porcine P-selectin cDNA resulted in surface expression of the protein and markedly increased the binding of human neutrophils to these cells. The binding of both soluble and COS-expressed porcine P-selectin to human neutrophils was blocked by pretreatment of the neutrophils with neuraminidase or the addition of EDTA. Finally, treatment of PAEC with human thrombin or normal human serum but not purified human C5a- or C8-deficient human serum resulted in the rapid expression of porcine P-selectin on the cell surface. CONCLUSIONS This report establishes that porcine P-selectin supports the binding of human neutrophils to PAEC in vitro. Further, these data suggest that sublytic deposition of C5b-9 during hyperacute rejection results in the expression of porcine P-selectin, which may contribute to the rapid adhesion of neutrophils to porcine xenografts.
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Affiliation(s)
- S A Rollins
- Alexion Pharmaceuticals, Inc., New Haven, Connecticut 06511, USA
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13
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Wang H, Rollins SA, Gao Z, Garcia B, Zhang Z, Xing J, Li L, Kellersmann R, Matis LA, Zhong R. Complement inhibition with an anti-C5 monoclonal antibody prevents hyperacute rejection in a xenograft heart transplantation model. Transplantation 1999; 68:1643-51. [PMID: 10609940 DOI: 10.1097/00007890-199912150-00007] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
BACKGROUND The present study was undertaken to determine whether anti-complement 5 (C5) monoclonal antibodies (mAb) prevent hyperacute rejection (HAR) in a rat-to-presensitized mouse heart transplantation model and whether these mAb, combined with cyclosporine (CsA) and cyclophosphamide (CyP), can achieve long-term graft survival. METHODS BALB/c mice were presensitized with 2x10(7) splenocytes from Lewis rats 14 days before grafting. Heart grafts from Lewis rats were heterotopically transplanted into BALB/c mice. Presensitized mice were treated with either anti-C5 mAb or a combination of anti-C5 mAb, CsA, and CyP. Controls included: presensitized mice with no treatment, presensitized mice treated with either CsA + CyP or IgG, and nonpresensitized mice with either no treatment or with CsA + CyP treatment. RESULTS Although typical features of HAR were evident in the presensitized grafts, the mAb completely inhibited complement activation and successfully prevented HAR. Despite complement inactivation, the graft was rejected on postoperative day 6 with acute vascular rejection (AVR) also known as delayed xenograft rejection (DXR). Notably, this type of rejection cannot be effectively overcome by CsA and CyP. CONCLUSIONS We conclude that (1) anti-C5 mAb prevents HAR, (2) AVR/DXR still occurs when HAR is prevented by complement inactivation, and (3) AVR/DXR cannot be overcome by conventional immunosuppression. These data suggest that anti-C5 mAb may be valuable for preventing HAR in future clinical xenotransplantation and that additional interventions may be required to address AVR/DXR.
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Affiliation(s)
- H Wang
- Department of Surgery, The University of Western Ontario, London, Canada
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14
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Rinder CS, Rinder HM, Smith MJ, Tracey JB, Fitch J, Li L, Rollins SA, Smith BR. Selective blockade of membrane attack complex formation during simulated extracorporeal circulation inhibits platelet but not leukocyte activation. J Thorac Cardiovasc Surg 1999; 118:460-6. [PMID: 10469960 DOI: 10.1016/s0022-5223(99)70183-2] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE Complement activation is induced by cardiopulmonary bypass, and previous work found that late complement components (C5a, C5b-9) contribute to neutrophil and platelet activation during bypass. In the present study, we blocked C5b-9 formation during extracorporeal recirculation of whole blood to assess whether the membrane attack complex was responsible for both platelet and leukocyte activation. METHODS In a simulated extracorporeal model that activates complement (C3a and sC5b-9), platelets (CD62P expression, leukocyte-platelet conjugate formation), and leukocytes (increased CD11b expression and neutrophil elastase), we examined an anti-human C8 monoclonal antibody that inhibits C5b-9 generation for its effects on cellular activation. RESULTS Anti-C8 significantly inhibited sC5b-9 formation but did not block C3a generation. Anti-C8 also significantly inhibited the increase in platelet CD62P and monocyte-platelet conjugate formation seen with control circulation. Moreover, compared with control circulation, in which the number of circulating platelets fell by 45%, addition of anti-C8 completely preserved platelet counts. In contrast to blockade of both C5a and sC5b-9 during simulated extracorporeal circulation, neutrophil activation was not inhibited by anti-C8. However, circulating neutrophil and monocyte counts were preserved by addition of anti-C8 to the extracorporeal circuit. CONCLUSIONS The membrane attack complex, C5b-9, is the major complement determinant of platelet activation during extracorporeal circulation, whereas C5b-9 blockade has little effect on neutrophil activation. These data also suggest a role for platelet activation or C5b-9 (or both) in the loss of monocytes and neutrophils to the extracorporeal circuit.
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Affiliation(s)
- C S Rinder
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Conn. 06510-8051, USA.
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15
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Vakeva AP, Agah A, Rollins SA, Matis LA, Li L, Stahl GL. Myocardial infarction and apoptosis after myocardial ischemia and reperfusion: role of the terminal complement components and inhibition by anti-C5 therapy. Circulation 1998; 97:2259-67. [PMID: 9631876 DOI: 10.1161/01.cir.97.22.2259] [Citation(s) in RCA: 280] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Myocardial ischemia and reperfusion (MI/R)-induced tissue injury involves necrosis and apoptosis. However, the precise contribution of apoptosis to cell death, as well as the mechanism of apoptosis induction, has not been delineated. In this study, we sought to define the contribution of the activated terminal complement components to apoptosis and necrosis in a rat model of MI/R injury. METHODS AND RESULTS Monoclonal antibodies (mAbs; 18A and 16C) raised against the rat C5 complement component bound to purified rat C5 (ELISA). 18A effectively blocked C5b-9-mediated cell lysis and C5a-induced chemotaxis of rat polymorphonuclear leukocytes (PMNs), whereas 16C had no complement inhibitor activity. A single dose (20 mg/kg i.v.) of 18A blocked >80% of serum hemolytic activity for >4 hours. Administration of 18A before myocardial ischemia (30 minutes) and reperfusion (4 hours) significantly reduced (91%) left ventricular free wall PMN infiltration compared with 16C treatment. Treatment with 18A 1 hour before ischemia or 5 minutes before reperfusion significantly reduced infarct size compared with 16C treatment. A significant reduction in infarct size (42%) was also observed in 18A-treated rats after 30 minutes of ischemia and 7 days of reperfusion. DNA ladders and DNA labeling (eg, TUNEL assay) demonstrated a dramatic reduction in MI/R-induced apoptosis in 18A-treated compared with 16C-treated rats. CONCLUSIONS Anti-C5 therapy in the setting of MI/R significantly inhibits cell apoptosis, necrosis, and PMN infiltration in the rat despite C3 deposition. We conclude that the terminal complement components C5a and C5b-9 are key mediators of tissue injury in MI/R.
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Affiliation(s)
- A P Vakeva
- Haartman Institute, Department of Bacteriology and Immunology, University of Helsinki, Finland
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16
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Thomas TC, Rollins SA, Rother RP, Giannoni MA, Hartman SL, Elliott EA, Nye SH, Matis LA, Squinto SP, Evans MJ. Inhibition of complement activity by humanized anti-C5 antibody and single-chain Fv. Mol Immunol 1996; 33:1389-401. [PMID: 9171898 DOI: 10.1016/s0161-5890(96)00078-8] [Citation(s) in RCA: 245] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Activation of the complement system contributes significantly to the pathogenesis of numerous acute and chronic diseases. Recently, a monoclonal antibody (5G1.1) that recognizes the human complement protein C5, has been shown to effectively block C5 cleavage, thereby preventing the generation of the pro-inflammatory complement components C5a and C5b-9. Humanized 5G1.1 antibody, Fab and scFv molecules have been produced by grafting the complementarity determining regions of 5G1.1 on to human framework regions. Competitive ELISA analysis indicated that no framework changes were required in the humanized variable regions for retention of high affinity binding to C5, even at framework positions predicted by computer modeling to influence CDR canonical structure. The humanized Fab and scFv molecules blocked complement-mediated lysis of chicken erythrocytes and porcine aortic endothelial cells in a dose-dependent fashion, with complete complement inhibition occurring at a three-fold molar excess, relative to the human C5 concentration. In contrast to a previously characterized anti-C5 scFv molecule, the humanized h5G1.1 scFv also effectively blocked C5a generation. Finally, an intact humanized h5G1.1 antibody blocked human complement lytic activity at concentrations identical to the original murine monoclonal antibody. These results demonstrate that humanized h5G1.1 and its recombinant derivatives retain both the affinity and blocking functions of the murine 5G1.1 antibody, and suggest that these molecules may serve as potent inhibitors of complement-mediated pathology in human inflammatory diseases.
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Affiliation(s)
- T C Thomas
- Alexion Pharmaceuticals, New Haven, CT 06511, USA
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17
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Wang Y, Hu Q, Madri JA, Rollins SA, Chodera A, Matis LA. Amelioration of lupus-like autoimmune disease in NZB/WF1 mice after treatment with a blocking monoclonal antibody specific for complement component C5. Proc Natl Acad Sci U S A 1996; 93:8563-8. [PMID: 8710910 PMCID: PMC38712 DOI: 10.1073/pnas.93.16.8563] [Citation(s) in RCA: 229] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
New Zealand black x New Zealand white (NZB/W) F1 mice spontaneously develop an autoimmune syndrome with notable similarities to human systemic lupus erythematosus. Female NZB/WF1 mice produce high titers of antinuclear antibodies and invariably succumb to severe glomerulonephritis by 12 months of age. Although the development of the immune-complex nephritis is accompanied by abundant local and systemic complement activation, the role of proinflammatory complement components in disease progression has not been established. In this study we have examined the contribution of activated terminal complement proteins to the pathogenesis of the lupus-like autoimmune disease. Female NZB/W F1 mice were treated with a monoclonal antibody (mAb) specific for the C5 component of complement that blocks the cleavage of C5 and thus prevents the generation of the potent proinflammatory factors C5a and C5b-9. Continuous therapy with anti-C5 mAb for 6 months resulted in significant amelioration of the course of glomerulonephritis and in markedly increased survival. These findings demonstrate an important role for the terminal complement cascade in the progression of renal disease in NZB/W F1 mice, and suggest that mAb-mediated C5 inhibition may be a useful approach to the therapy of immune-complex glomerulonephritis in humans.
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Affiliation(s)
- Y Wang
- Immunobiology Program, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
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Kroshus TJ, Bolman RM, Dalmasso AP, Rollins SA, Guilmette ER, Williams BL, Squinto SP, Fodor WL. Expression of human CD59 in transgenic pig organs enhances organ survival in an ex vivo xenogeneic perfusion model. Transplantation 1996; 61:1513-21. [PMID: 8633381 DOI: 10.1097/00007890-199605270-00018] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The serious shortage of available donor organs for patients with end stage organ failure who are in need of solid organ transplantation has led to a heightened interest in xenotransplantation. The major barrier to successful discordant xenotransplantation is hyperacute rejection. Hyperacute rejection results from the deposition of preformed antibodies that activate complement on the luminal surface of the vascular endothelium, leading to vessel occlusion and graft failure within minutes to hours. Endogenous membrane-associated complement inhibitors normally protect endothelial cells from autologous complement -- however, these molecules are species-restricted and therefore are ineffective at inhibiting activated xenogeneic complement. To address the pathogenesis of hyperacute rejection in the pig-to-human combination, F1 offspring were generated from a transgenic founder animal that was engineered to express the human terminal complement inhibitor hCD59. High-level cell surface expression of hCD59 was detected in the hearts and kidneys of these transgenic F1 animals, similar to expression levels in human kidney tissue. The hCD59 was expressed on both large vessel and capillary endothelium. Ex vivo perfusion experiments, using human blood as the perfusate, were performed with transgenic porcine hearts and kidneys to evaluate the ability of hCD59 to inhibit hyperacute rejection. These experiments demonstrated that transgenic organs expressing hCD69 resisted hyperacute rejection, as measured by increased organ function for both the hearts and the kidneys, as compared with control pig organs. Hearts from hCD59-expressing animals demonstrated a five-fold prolongation in function compared with controls, 109.8 +/- 20.7 min versus 21.2 +/- 2.9 min (P = 0.164). The hCD59-expressing kidneys also demonstrated significantly prolonged function at 157.8 +/- 27.0 min compared with 60.0 +/- 6.1 min for controls (P = 0.0174). Deposition of C9 neoantigen In the vasculature of porcine organs perfused with human blood was markedly reduced in organs expressing hCD59. These studies demonstrate that C5b-9 plays an important role in hyperacute rejection of a porcine organ perfused with human blood and suggest that donor pigs transgenic for hCD59 may be an integral component of successful clinical xenotransplantation.
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Affiliation(s)
- T J Kroshus
- Department of Surgery, University of Minnesota, Minneapolis, USA
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Rollins SA, Birks CW, Setter E, Squinto SP, Rother RP. Retroviral vector producer cell killing in human serum is mediated by natural antibody and complement: strategies for evading the humoral immune response. Hum Gene Ther 1996; 7:619-26. [PMID: 8845387 DOI: 10.1089/hum.1996.7.5-619] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The introduction of retroviral vector producer cells (VPC) into tumors as a means of increasing transduction efficiency has recently been employed in human gene therapy trials. However, the fate of these xenogeneic cells in humans is not well understood. In the present study, we used an in vitro model to examine the survival of commonly used VPC lines in serum from humans and various other species. VPC derived from the murine NIH-3T3 cell line, including PA317, Psi CRIP, and GP + E-86, were effectively killed in sera from Old World primates, including human and baboon. Conversely, the same murine cell lines survived exposure to sera from dog, rabbit, rat, and mouse. This pattern of serum killing parallels the occurrence of the anti-alpha-galactosyl natural antibody (Ab) found exclusively in Old World primates. The anti-alpha-galactosyl Ab targets the terminal glycosidic structure Gal alpha 1-3Gal beta 1-4GlcNAc-R (alpha-galactosyl epitope) found on the surface of mammalian cells, excluding Old World primates. All murine-derived VPC tested expressed high levels of the alpha-galactosyl epitope as determined by FACS analysis. VPC killing was complement-mediated, because preincubation of human serum with a functionally blocking anti-C5 mAb completely abolished cell lysis. Furthermore, addition of soluble galactose(alpha 1-3)galactose (Gal alpha 1-3Gal) to human serum or down-regulation of the alpha-galactosyl epitope on the surface of VPC effectively reduced VPC killing, indicating that complement activation by these cells is primarily initiated by natural antibody recognition of the alpha-galactosyl epitope. Finally, VPC incubated with human serum for 8 hr in the presence of complement inhibition continued to produce viable retroviral particles, thus demonstrating a correlation between VPC and particle survival. Taken together, these data suggest that elimination of the alpha-galactosyl epitope or complement blockade may provide a strategy to prolong the survival of VPC and the particles that they produce in vivo.
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Affiliation(s)
- S A Rollins
- Department of Immunobiology, Alexion Pharmaceuticals Inc., New Haven, CT 06511, USA
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Sandrin MS, Fodor WL, Cohney S, Mouhtouris E, Osman N, Rollins SA, Squinto SP, McKenzie IFC. Reduction of the major porcine xenoantigen Galoc(1,3)Gal by expression of α(1,2)fucosyltransferase. Xenotransplantation 1996. [DOI: 10.1111/j.1399-3089.1996.tb00130.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Kroshus TJ, Rollins SA, Dalmasso AP, Elliott EA, Matis LA, Squinto SP, Bolman RM. Complement inhibition with an anti-C5 monoclonal antibody prevents acute cardiac tissue injury in an ex vivo model of pig-to-human xenotransplantation. Transplantation 1995; 60:1194-202. [PMID: 8525509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Prevention of hyperacute xenograft rejection in the pig-to-primate combination has been accomplished by removal of natural antibodies, complement depletion with cobra venom factor, or prevention of C3 activation with the soluble complement inhibitor sCR1. Although these strategies effectively prevent hyperacute rejection, they do not address the relative contribution of early (C3a, C3b) versus late (C5a, C5b-9) activated complement components to xenogeneic organ damage. To better understand the role of the terminal complement components (C5a, C5b-9) in hyperacute rejection, an anti-human C5 mAb was developed and tested in an ex vivo model of cardiac xenograft rejection. In vitro studies demonstrated that the anti-C5 mAb effectively blocked C5 cleavage in a dose-dependent manner that resulted in complete inhibition of both C5a and C5b-9 generation. Addition of anti-C5 mAb to human blood used to perfuse a porcine heart prolonged normal sinus cardiac rhythm from a mean time of 25.2 min in hearts perfused with unmodified blood to 79,296, or > 360 min when anti-C5 mAb was added to the blood at 50 micrograms/ml, 100 micrograms/ml, or 200 micrograms/ml, respectively. In these experiments, activation of the classical complement pathway was completely inhibited. Hearts perfused with blood containing the highest concentration of anti-C5 mAb had no histologic evidence of hyperacute rejection and no deposition of C5b-9. These experiments suggest that the activated terminal complement components C5a and C5b-9, but not C3a or C3b, play a major role in tissue damage in this porcine-to-human model of hyperacute rejection. They also suggest that targeted inhibition of terminal complement activation by anti-C5 mAbs may be useful in clinical xenotransplantation.
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Affiliation(s)
- T J Kroshus
- Department of Surgery, University of Minnesota, Minneapolis 55455, USA
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Rollins SA, Matis LA, Springhorn JP, Setter E, Wolff DW. Monoclonal antibodies directed against human C5 and C8 block complement-mediated damage of xenogeneic cells and organs. Transplantation 1995; 60:1284-92. [PMID: 8525523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The hyperacute rejection (HAR) of xenotransplanted organs is initiated by the deposition of natural antibodies on donor endothelium followed by the activation of the recipient complement system, which rapidly destroys the graft. Studies of the role of activated complement in HAR have suggested that natural antibody as well as early (C3a, C3b) and late (C5a, C5b-9) activated complement components may contribute to cell activation and damage. Attenuation of HAR has been achieved by blockade of C3 activation with soluble CR1 or consumptive depletion of complement with cobra venom factor; however, similar studies using specific inhibitors of terminal complement components have not been described. To address the contribution of C5a and the membrane attack complex (C5b-9, MAC) to complement-mediated xenogeneic cell and organ damage, we utilized functionally blocking monoclonal antibodies directed against the human terminal complement components C5 and C8. Our data show that both anti-C5 and anti-C8 mAbs protect porcine aortic endothelial cells from membrane damage mediated by human C5b-9. Additionally, both the anti-C5 and anti-C8 mAbs blocked complement-mediated generation of membrane prothrombinase activity on porcine aortic endothelial cells challenged with human serum. To test the ability of these antibodies to attenuate antibody and complement-mediated damage of xenogeneic organs, an ex vivo model was developed wherein isolated rat hearts were perfused with human serum in the presence or absence of the anti-C5 and anti-C8 mAbs. Our data demonstrate that mAbs directed against human C5 and C8 prevented organ damage by human serum complement and suggest that these molecules may serve as potent inhibitors of HAR.
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Affiliation(s)
- S A Rollins
- Department of Immunobiology, Alexion Pharmaceuticals, Inc., New Haven, Connecticut 06511, USA
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Sandrin MS, Fodor WL, Mouhtouris E, Osman N, Cohney S, Rollins SA, Guilmette ER, Setter E, Squinto SP, McKenzie IF. Enzymatic remodelling of the carbohydrate surface of a xenogenic cell substantially reduces human antibody binding and complement-mediated cytolysis. Nat Med 1995; 1:1261-7. [PMID: 7489406 DOI: 10.1038/nm1295-1261] [Citation(s) in RCA: 262] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The major obstacle to successful discordant xenotransplantation is the phenomenon of hyperacute rejection (HAR). In the pig-to-primate discordant transplant setting, HAR results from the deposition of high-titre anti-alpha-galactosyl antibodies and complement activation leading to endothelial cell destruction and rapid graft failure. To overcome HAR, we developed an enzymatic carbohydrate remodelling strategy designed to replace expression of the Gal alpha-1,3-Gal xenoepitope on the surface of porcine cells with the non-antigenic universal donor human blood group O antigen, the alpha-1,2-fucosyl lactosamine moiety (H-epitope). Xenogenic cells expressing the human alpha-1,2-fucosyltransferase expressed high levels of the H-epitope and significantly reduced Gal alpha-1,3-Gal expression. As a result, these cells were shown to be resistant to human natural antibody binding and complement-mediated cytolysis.
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Affiliation(s)
- M S Sandrin
- Molecular Immunogenetics Laboratory, Austin Research Institute, Heidelberg, Vic., Australia
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Fodor WL, Rollins SA, Guilmette ER, Setter E, Squinto SP. A novel bifunctional chimeric complement inhibitor that regulates C3 convertase and formation of the membrane attack complex. The Journal of Immunology 1995. [DOI: 10.4049/jimmunol.155.9.4135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
Human cells express cell surface complement regulatory molecules that inhibit the activity of the C3/C5 convertases (DAF, MCP, CR1) or inhibit the membrane attack complex (CD59). A single molecule that inhibits both the convertase activity and formation of the membrane attack complex has never been characterized. To this end, we have developed two reciprocal chimeric complement inhibitors (CD, NH2-CD59-DAF-GPI; and DC, NH2-DAF-CD59-GPI) that contain the functional domains of decay accelerating factor (DAF; CD55) and CD59. Cell surface expression of the CD and DC chimeric proteins was detected with DAF- and CD59-specific antisera. Cell surface C3d deposition was inhibited on cells expressing the chimeric molecules, thereby indicating that the DAF moiety was functional in both molecules. Conversely, Ab-blocking experiments demonstrated that only the DC molecule retained CD59 function. Therefore, the DC molecule represents a novel potent chimeric bifunctional complement inhibitor that retains the functional domains of two distinct complement regulatory molecules.
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Affiliation(s)
- W L Fodor
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
| | - S A Rollins
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
| | - E R Guilmette
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
| | - E Setter
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
| | - S P Squinto
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
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Rother RP, Fodor WL, Springhorn JP, Birks CW, Setter E, Sandrin MS, Squinto SP, Rollins SA. A novel mechanism of retrovirus inactivation in human serum mediated by anti-alpha-galactosyl natural antibody. J Exp Med 1995; 182:1345-55. [PMID: 7595205 PMCID: PMC2192220 DOI: 10.1084/jem.182.5.1345] [Citation(s) in RCA: 152] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Type C retroviruses endogenous to various nonprimate species can infect human cells in vitro, yet the transmission of these viruses to humans is restricted. This has been attributed to direct binding of the complement component C1q to the viral envelope protein p15E, which leads to classical pathway-mediated virolysis in human serum. Here we report a novel mechanism of complement-mediated type C retrovirus inactivation that is initiated by the binding of "natural antibody" [Ab] (anti-alpha-galactosyl Ab) to the carbohydrate epitope Gal alpha 1-3Gal beta 1-4GlcNAc-R expressed on the retroviral envelope. Complement-mediated inactivation of amphotropic retroviral particles was found to be restricted to human and other Old World primate sera, which parallels the presence of anti-alpha-galactosyl natural Ab. Blockade or depletion of anti-alpha-galactosyl Ab in human serum prevented inactivation of both amphotropic and ecotropic murine retroviruses. Similarly, retrovirus was not killed by New World primate serum except in the presence of exogenous anti-alpha-galactosyl Ab. Enzyme-linked immunosorbent assays revealed that the alpha-galactosyl epitope was expressed on the surface of amphotropic and ecotropic retroviruses, and Western blot analysis further localized this epitope to the retroviral envelope glycoprotein gp70. Finally, down-regulation of this epitope on the surface of murine retroviral particle producer cells rendered them, as well as the particles liberated from these cells, resistant to inactivation by human serum complement. Our data suggest that anti-alpha-galactosyl Ab may provide a barrier for the horizontal transmission of retrovirus from species that express the alpha-galactosyl epitope to humans and to other Old World primates. Further, these data provide a mechanism for the generation of complement-resistant retroviral vectors for in vivo gene therapy applications where exposure to human complement is unavoidable.
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Affiliation(s)
- R P Rother
- Department of Molecular Development, Alexion Pharmaceuticals Inc., New Haven, Connecticut 06511, USA
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27
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Evans MJ, Rollins SA, Wolff DW, Rother RP, Norin AJ, Therrien DM, Grijalva GA, Mueller JP, Nye SH, Squinto SP. In vitro and in vivo inhibition of complement activity by a single-chain Fv fragment recognizing human C5. Mol Immunol 1995; 32:1183-95. [PMID: 8559143 DOI: 10.1016/0161-5890(95)00099-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Complement activation has been implicated in the pathogenesis of several human diseases. Recently, a monoclonal antibody, (N19-8) that recognizes the human complement protein C5 has been shown to effectively block the cleavage of C5 into C5a and C5b, thereby blocking terminal complement activation. In this study, a recombinant N19-8 scFv antibody fragment was constructed from the N19-8 variable regions, and produced in both mammalian and bacterial cells. The N19-8 scFv bound human C5 and was as potent as the N19-8 monoclonal antibody at inhibiting human C5b-9-mediated hemolysis of chicken erythrocytes. In contrast, the N19-8 scFv only partially retained the ability of the N19-8 monoclonal antibody to inhibit C5a generation. To investigate the ability of the N19-8 scFv to inhibit complement-mediated tissue damage, complement-dependent myocardial injury was induced in isolated mouse hearts by perfusion with Krebs-Henseleit buffer containing 6% human plasma. The perfused hearts sustained extensive deposition of human C3 and C5b-9, resulting in increased coronary artery perfusion pressure, end-diastolic pressure, and a decrease in heart rate until the hearts ceased beating approximately 10 min after addition of plasma. Hearts treated with human plasma supplemented with either the N19-8 monoclonal antibody or the N19-8 scFv did not show any detectable changes in cardiac performance for at least 1 hr following the addition of plasma. Hearts treated with human plasma alone showed extensive deposition of C3 and C5b-9, while hearts treated with human plasma containing N19-8 scFv showed extensive deposition of C3, but no detectable deposition of C5b-9. Administration of a 100 mg bolus dose of N19-8 scFv to rhesus monkeys inhibited the serum hemolytic activity by at least 50% for up to 2 hr. Pharmacokinetic analysis of N19-8 scFv serum levels suggested a two-compartment model with a T1/2 alpha of 27 min. Together, these data suggest the recombinant N19-8 scFv is a potent inhibitor of the terminal complement cascade and may have potential in vivo applications where short duration inhibition of terminal complement activity is desirable.
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Affiliation(s)
- M J Evans
- Department of Molecular Development, Alexion Pharmaceuticals, New Haven, CT 06511, USA
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28
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Fodor WL, Rollins SA, Guilmette ER, Setter E, Squinto SP. A novel bifunctional chimeric complement inhibitor that regulates C3 convertase and formation of the membrane attack complex. J Immunol 1995; 155:4135-8. [PMID: 7594566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Human cells express cell surface complement regulatory molecules that inhibit the activity of the C3/C5 convertases (DAF, MCP, CR1) or inhibit the membrane attack complex (CD59). A single molecule that inhibits both the convertase activity and formation of the membrane attack complex has never been characterized. To this end, we have developed two reciprocal chimeric complement inhibitors (CD, NH2-CD59-DAF-GPI; and DC, NH2-DAF-CD59-GPI) that contain the functional domains of decay accelerating factor (DAF; CD55) and CD59. Cell surface expression of the CD and DC chimeric proteins was detected with DAF- and CD59-specific antisera. Cell surface C3d deposition was inhibited on cells expressing the chimeric molecules, thereby indicating that the DAF moiety was functional in both molecules. Conversely, Ab-blocking experiments demonstrated that only the DC molecule retained CD59 function. Therefore, the DC molecule represents a novel potent chimeric bifunctional complement inhibitor that retains the functional domains of two distinct complement regulatory molecules.
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Affiliation(s)
- W L Fodor
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
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Wang Y, Rollins SA, Madri JA, Matis LA. Anti-C5 monoclonal antibody therapy prevents collagen-induced arthritis and ameliorates established disease. Proc Natl Acad Sci U S A 1995; 92:8955-9. [PMID: 7568051 PMCID: PMC41086 DOI: 10.1073/pnas.92.19.8955] [Citation(s) in RCA: 251] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Activated components of the complement system are potent mediators of inflammation that may play an important role in numerous disease states. For example, they have been implicated in the pathogenesis of inflammatory joint diseases including rheumatoid arthritis (RA). To target complement activation in immune-mediated joint inflammation, we have utilized monoclonal antibodies (mAbs) that inhibit the complement cascade at C5, blocking the generation of the major chemotactic and proinflammatory factors C5a and C5b-9. In this study, we demonstrate the efficacy of a mAb specific for murine C5 in the treatment of collagen-induced arthritis, an animal model for RA. We show that systemic administration of the anti-C5 mAb effectively inhibits terminal complement activation in vivo and prevents the onset of arthritis in immunized animals. Most important, anti-C5 mAb treatment is also highly effective in ameliorating established disease. These results demonstrate a critical role for activated terminal complement components not only in the induction but also in the progression of collagen-induced arthritis and suggest that C5 may be an attractive therapeutic target in RA.
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Affiliation(s)
- Y Wang
- Immunobiology Program, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
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30
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Rinder CS, Rinder HM, Smith BR, Fitch JC, Smith MJ, Tracey JB, Matis LA, Squinto SP, Rollins SA. Blockade of C5a and C5b-9 generation inhibits leukocyte and platelet activation during extracorporeal circulation. J Clin Invest 1995; 96:1564-72. [PMID: 7657827 PMCID: PMC185782 DOI: 10.1172/jci118195] [Citation(s) in RCA: 177] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Complement activation contributes to the systemic inflammatory response induced by cardiopulmonary bypass. At the cellular level, cardiopulmonary bypass activates leukocytes and platelets; however the contribution of early (3a) versus late (C5a, soluble C5b-9) complement components to this activation is unclear. We used a model of simulated extracorporeal circulation that activates complement (C3a, C5a, and C5b-9 formation), platelets (increased percentages of P-selectin-positive platelets and leukocyte-platelet conjugates), and neutrophils (upregulated CD11b expression). to specifically target complement activation in this model, we added a blocking mAb directed at the human C5 complement component and assessed its effect on complement and cellular activation. Compared with a control mAB, the anti-human C5 mAb profoundly inhibited C5a and soluble C5b-9 generation and serum complement hemolytic activity but had no effect on C3a generation. Additionally, the anti-human C5 mAb significantly inhibited neutrophil CD11b upregulation and abolished the increase in P-selectin-positive platelets and leukocyte-platelet conjugate formation compared to experiments performed with the control mAb. This suggests that the terminal components C5a and C5b-9, but not C3a, directly contribute to platelet and neutrophil activation during extracorporeal circulation. Furthermore, these data identify the C5 component as a site for therapeutic intervention in cardiopulmonary bypass.
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Affiliation(s)
- C S Rinder
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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31
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Evans MJ, Hartman SL, Wolff DW, Rollins SA, Squinto SP. Rapid expression of an anti-human C5 chimeric Fab utilizing a vector that replicates in COS and 293 cells. J Immunol Methods 1995; 184:123-38. [PMID: 7622864 DOI: 10.1016/0022-1759(95)00093-p] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Inhibition of complement system activation requires the development of soluble nonimmunogenic inhibitors with good tissue penetrating abilities that are themselves unable to activate complement. Chimeric mouse/human Fabs capable of blocking the activity of complement proteins are likely to fulfill these criteria. Several monoclonal antibodies that inhibit the activation of the human complement system have recently been developed. To examine the properties of chimeric Fab derived from these monoclonal antibodies, we have developed an expression system which allows the rapid production of milligram quantities of chimeric Fab. Both the chimeric light chain and the chimeric Fd were co-expressed from the same vector, pAPEX-3P. This vector contains the SV40 origin of replication, which allows the rapid production of chimeric Fab in COS cells for preliminary characterization. Additionally, pAPEX-3P contains the Epstein-Barr virus origin of replication and a puromycin selectable marker for maintenance as a stable episome in human cell lines. A production system consisting of transfected 293-EBNA cells cultured in serum free medium followed by protein G-Sepharose chromatography of the conditioned medium was found to be sufficient for the rapid production of purified chimeric Fab. Here we have utilized this expression system to demonstrate that an anti-human C5 chimeric Fab was a potent inhibitor of complement activation in both in vitro activation assays and an ex vivo model of complement-mediated tissue damage.
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Affiliation(s)
- M J Evans
- Department of Molecular Development, Alexion Pharmaceuticals, Inc., New Haven, CT 06511, USA
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32
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Fodor WL, Rollins SA, Bianco-Caron S, Rother RP, Guilmette ER, Burton WV, Albrecht JC, Fleckenstein B, Squinto SP. The complement control protein homolog of herpesvirus saimiri regulates serum complement by inhibiting C3 convertase activity. J Virol 1995; 69:3889-92. [PMID: 7745740 PMCID: PMC189111 DOI: 10.1128/jvi.69.6.3889-3892.1995] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The herpesvirus saimiri genome encodes a complement control protein homolog (CCPH). Stable mammalian cell transfectants expressing a recombinant transmembrane form of CCPH (mCCPH) or a 5'FLAG epitope-tagged mCCPH (5'FLAGmCCPH) conferred resistance to complement-mediated cell damage by inhibiting the lytic activity of human serum complement. The function of CCPH was further defined by showing that the mCCPH and the 5'FLAGmCCPH transfectants inhibited C3 convertase activity and effectively reduced cell surface deposition of the activated complement component, C3d.
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Affiliation(s)
- W L Fodor
- Alexion Pharmaceuticals Inc., New Haven, Connecticut 06511, USA
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Abstract
The rapid inactivation of murine-derived retroviral vectors in human or nonhuman primate sera is largely attributed to the activity of complement mediated through the classical pathway. In this study, we have further investigated the relationship between the human complement cascade and retrovirus inactivation. Preincubation in normal human serum effectively inactivated LXSN retroviral vector particles, whereas the vector maintained the ability to transduce cells following incubation in sera deficient in either the C1, C2, C3, C5, C6, C8, or C9 human complement proteins. Preincubation of serum with monoclonal antibodies (mAbs) that functionally block specific complement components, including C5, C6, C8, and C9, successfully protected the LXSN vector from complement-mediated inactivation. Treatment of serum with cobra venom factor, which consumes terminal complement, also effectively protected the vector from inactivation. LXSN vector survival in serum corresponded inversely to the level of complement activity following treatment of serum with anti-C5 mAb as assessed in an erythrocyte hemolytic assay. Additionally, pretreatment of human whole blood with anti-C5 mAb effectively inhibited inactivation of the LXSN vector. Taken together, these data demonstrate that formation of the membrane attack complex (MAC, C5b-9) is required for the inactivation of the murine-based LXSN retroviral vector in human blood and that this process can be abrogated with the use of soluble complement inhibitors.
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Affiliation(s)
- R P Rother
- Department of Molecular Development, Alexion Pharmaceuticals Inc., New Haven, CT 06511, USA
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Fodor WL, Rollins SA, Bianco-Caron S, Burton WV, Guilmette ER, Rother RP, Zavoico GB, Squinto SP. Primate terminal complement inhibitor homologues of human CD59. Immunogenetics 1995; 41:51. [PMID: 7528724 DOI: 10.1007/bf00188435] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- W L Fodor
- Alexion Pharmaceuticals, Inc., New Haven, CT 06511-1968
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35
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Affiliation(s)
- L A Matis
- Immunobiology Program, Alexion Pharmaceuticals, Inc., New Haven, Connecticut 06511, USA
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Fodor WL, Williams BL, Matis LA, Madri JA, Rollins SA, Knight JW, Velander W, Squinto SP. Expression of a functional human complement inhibitor in a transgenic pig as a model for the prevention of xenogeneic hyperacute organ rejection. Proc Natl Acad Sci U S A 1994; 91:11153-7. [PMID: 7526391 PMCID: PMC45185 DOI: 10.1073/pnas.91.23.11153] [Citation(s) in RCA: 266] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The serious shortage of human organs available for transplantation has engendered a heightened interest in the use of animal organs (xenografts) for transplantation. However, the major barrier to successful discordant xenogeneic organ transplantation is the phenomenon of hyperacute rejection. Hyperacute rejection results from the deposition of high-titer preformed antibodies that activate serum complement on the luminal surface of the vascular endothelium, leading to vessel occlusion and graft failure within minutes to hours. Although endogenous membrane-associated complement inhibitors normally protect endothelial cells from autologous complement, they are species restricted and thus confer limited resistance to activated xenogeneic complement. To address the pathogenesis of hyperacute rejection in xenotransplantation, transgenic mice and a transgenic pig were engineered to express the human terminal complement inhibitor hCD59. High-level cell surface expression of hCD59 was achieved in a variety of murine and porcine cell types, most importantly on both large vessel and capillary endothelium. hCD59-expressing porcine cells were significantly resistant to challenge with high-titer anti-porcine antibody and human complement. These experiments demonstrate a strategy for developing a pig-to-primate xenogeneic transplantation model to test whether the expression of a human complement inhibitor in transgenic pigs could render xenogeneic organs resistant to hyperacute rejection.
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Affiliation(s)
- W L Fodor
- Alexion Pharmaceuticals, Inc., New Haven, CT 06511
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Rollins SA, Evans MJ, Johnson KK, Elliot EA, Squinto SP, Matis LA, Rother RP. Molecular and functional analysis of porcine E-selectin reveals a potential role in xenograft rejection. Biochem Biophys Res Commun 1994; 204:763-71. [PMID: 7526854 DOI: 10.1006/bbrc.1994.2525] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In this study, we report the molecular and functional characterization of porcine E-selectin. Incubation of porcine endothelial cells with human TNF alpha but not human IL-1 resulted in a marked increase in binding to human neutrophils. In order to confirm that this interaction was mediated by E-selectin, we isolated the full-length porcine E-selectin cDNA which contained an open reading frame encoding 485 amino acids with 75% identity to human E-selectin. Expression or recombinant porcine E-selectin in COS cells resulted in surface expression of the protein and increased binding to human neutrophils. Northern blot analysis showed that treatment of porcine endothelial cells with human TNF alpha but not human IL-1 resulted in high levels of porcine E-selectin mRNA. Taken together, our data establish that porcine E-selectin mediates adhesive interactions between porcine endothelial cells and human leukocytes that may contribute to xenograft rejection.
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Affiliation(s)
- S A Rollins
- Department of Immunobiology, Alexion Pharmaceuticals, Inc., New Haven, CT 06511
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Rother RP, Rollins SA, Mennone J, Chodera A, Fidel SA, Bessler M, Hillmen P, Squinto SP. Expression of recombinant transmembrane CD59 in paroxysmal nocturnal hemoglobinuria B cells confers resistance to human complement. Blood 1994; 84:2604-11. [PMID: 7522635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired hematopoietic disorder characterized by complement-mediated hemolytic anemia, pancytopenia, and venous thrombosis. These clinical manifestations arise from an underlying molecular defect of bone marrow stem cells. Specifically, somatic mutations in the phosphatidylinositol glycan class A gene result in the ability of blood cells to anchor complement-regulatory proteins (CD59 and DAF) to the cell surface via glycosyl phosphatidylinositol (GPI). In an attempt to circumvent the functional defect in PNH cells, a recombinant transmembrane form of CD59 (CD59-TM) was analyzed for the ability to regulate complement activity. Balb/3T3 stable transfectants expressing similar levels of either CD59-TM or native CD59 (CD59-GPI) were equally protected against human complement-mediated membrane damage. Treatment of these cells with phosphatidylinositol-specific phospholipase C failed to release CD59-TM from the cell surface. Retroviral transduction of GPI-anchoring deficient mouse L cells with CD59-TM resulted in surface expression of the protein and rendered these cells resistant to human complement-mediated membrane damage. Conversely, L cells transduced with CD59-GPI failed to express this protein on the cell surface. A GPI-anchoring deficient complement-sensitive B-cell line derived from a PNH patient was successfully transduced with CD59-TM, resulting in surface expression of the protein. The PNH B cells expressing CD59-TM were protected against classical complement-mediated membrane damage by human serum. Taken together, these data establish that a functional recombinant transmembrane form of CD59 can be expressed on the surface of GPI-anchoring deficient PNH cells and suggest that retroviral gene therapy with this molecule could provide a treatment for PNH patients.
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Affiliation(s)
- R P Rother
- Alexion Pharmaceuticals Inc, New Haven, CT
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Rollins SA, Kennedy SP, Chodera AJ, Elliott EA, Zavoico GB, Matis LA. Evidence that activation of human T cells by porcine endothelium involves direct recognition of porcine SLA and costimulation by porcine ligands for LFA-1 and CD2. Transplantation 1994; 57:1709-16. [PMID: 7912457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In this study we present a comprehensive evaluation of the molecular interactions between human T cells and porcine aortic endothelial cells (PAEC) that contribute to human T cell activation. Binding assays demonstrated that porcine erythrocytes (E) and PAEC express ligand(s) for the human T cell glycoprotein CD2. Prior incubation of human T cells with a blocking monoclonal antibody directed against CD2 (alpha CD2-BL) completely inhibited T cell/E and T cell/PAEC interaction. Xenogeneic mixed lymphocyte reactions (XMLR) revealed that human PBMC, or highly purified T cells were activated by PAEC in the absence of human antigen-presenting cells (APC). Addition of alpha CD2-BL or alpha LFA-1 to these assays inhibited PAEC-mediated human T cell activation. Furthermore, we demonstrated that highly purified human CD4+ and CD8+ T cells proliferated in response to PAEC and that this response was blocked by monoclonal antibodies directed against LFA-1 and CD2. Addition of alpha SLA class I blocked the proliferation of CD8+ but not CD4+ T cells, indicating direct presentation of SLA class I antigens to human T cells. We have recently shown that expression of the human complement inhibitor (CD59) on PAEC (PAEC-LXSNCD59) rendered these cells resistant to human complement-mediated activation and lysis, suggesting that human CD59 expression on PAEC could be an effective therapy for hyperacute rejection (HAR). However, recent studies have shown that in addition to its role as a complement inhibitor, CD59 binds human T cell CD2 and contributes to T cell activation. We therefore examined whether human CD59 expression on PAEC augmented the human antiporcine T cell response. We demonstrated that human T cells do not display increased binding to or activation by PAEC-LXSNCD59 relative to PAEC controls. Taken together, our data establish that PAEC directly stimulate human T cells in vitro and that interactions between the human accessory molecules CD2, LFA-1 and their PAEC surface ligands contribute to human T cell activation. In addition, the expression of human CD59 on porcine donor organs may confer resistance to human complement-mediated HAR without exacerbating the human antiporcine cellular response.
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Affiliation(s)
- S A Rollins
- Department of Immunobiology, Alexion Pharmaceuticals, Inc., New Haven Connecticut 06511
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Kennedy SP, Rollins SA, Burton WV, Sims PJ, Bothwell AL, Squinto SP, Zavoico GB. Protection of porcine aortic endothelial cells from complement-mediated cell lysis and activation by recombinant human CD59. Transplantation 1994; 57:1494-501. [PMID: 7515200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Discordant xenogeneic organ transplantation is a potential solution to the critical shortage of suitable donor organs. However, clinical application of xenotransplantation with physiologically suitable organs such as those from the pig, is currently limited by the lack of agents to prevent antibody and complement-mediated hyperacute rejection of the transplanted organ. We have used retrovirus-mediated gene transfer to express the terminal complement inhibitor protein, human CD59, in neonatal porcine aortic endothelial cells (nPAEC). Human CD59 was constitutively expressed in nPAECs at levels similar to that of native CD59 in human umbilical vein endothelial cells. The protein was tethered to the cell surface by a glycosyl-phosphatidylinositol anchor, as demonstrated by its removal following treatment with phosphatidylinositol-specific phospholipase C. In a model of antibody-dependent complement activation, nPAECs expressing human CD59 were protected from membrane pore formation and cell lysis by complement derived from either human or baboon sera. Conversely, nPAECs expressing CD59 were not protected from lysis by rabbit or dog complement, indicating that recombinant CD59 retained its species-restricted inhibitory activity. Additionally, CD59 expressed on nPAECs inhibited the C5b-9-dependent generation of membrane prothrombinase activity. Collectively, these data establish that stable expression of human CD59 on xenotypic (porcine) endothelial cells renders these cells resistant to both the cytolytic and procoagulant effects of human complement. We propose that expression of recombinant human CD59 on porcine donor organs may prevent complement-mediated lysis and activation of endothelial cells that leads to hyperacute rejection.
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Affiliation(s)
- S P Kennedy
- Department of Vascular Biology, Alexion Pharmaceuticals, Inc., New Haven 06511
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Rother RP, Rollins SA, Fodor WL, Albrecht JC, Setter E, Fleckenstein B, Squinto SP. Inhibition of complement-mediated cytolysis by the terminal complement inhibitor of herpesvirus saimiri. J Virol 1994; 68:730-7. [PMID: 7507185 PMCID: PMC236509 DOI: 10.1128/jvi.68.2.730-737.1994] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Herpesvirus saimiri (HVS) is a lymphotropic herpesvirus that induces T-cell transformation in vitro and causes lymphomas and leukemias in New World primates other than its natural host, the squirrel monkey. Nucleotide sequence analysis of the HVS genome revealed two open reading frames with significant homology to genes for human complement regulatory molecules. One of these genes encodes a predicted protein (designated HVSCD59) with 48% amino acid sequence identity to the human terminal complement regulatory protein CD59 (HuCD59). The CD59 homolog from squirrel monkey (SMCD59) was cloned, and the corresponding amino acid sequence showed 69% identity with HVSCD59. BALB/3T3 cells stably expressing HVSCD59, SMCD59, or HuCD59 were equally protected from complement-mediated lysis by human serum. However, only HVSCD59-expressing cells were effectively protected from complement-mediated lysis when challenged with rat serum, suggesting that HVSCD59 was less species restrictive. The complement regulatory activity of HVSCD59 and SMCD59 occurred after C3b deposition, indicating terminal complement inhibition. Treatment of BALB/3T3 stable transfectants with phosphatidylinositol-specific phospholipase C prior to complement attack decreased the complement regulatory function of HVSCD59, suggesting cell surface attachment via a glycosyl-phosphatidylinositol anchor. Cells expressing HVSCD59 effectively inhibited complement-mediated lysis by squirrel monkey serum in comparison with SMCD59-expressing cells. Finally HVSCD59-specific transcripts were detected in owl monkey cells permissive for lytic HVS replication but not in T cells transformed by HVS, which failed to produce virions. These data are the first to demonstrate a functional, virally encoded terminal complement inhibitor and suggest that HVSCD59 represents a humoral immune evasion mechanism supporting the lytic life cycle of HVS.
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Affiliation(s)
- R P Rother
- Alexion Pharmaceuticals Inc., New Haven, Connecticut 06511
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Ninomiya H, Stewart BH, Rollins SA, Zhao J, Bothwell AL, Sims PJ. Contribution of the N-linked carbohydrate of erythrocyte antigen CD59 to its complement-inhibitory activity. J Biol Chem 1992; 267:8404-10. [PMID: 1373727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The contribution of N-linked carbohydrate to the complement-inhibitory function of the human erythrocyte membrane glycoprotein, CD59, was investigated. Amino acid sequence analysis of tryptic peptides labeled with [3H]borohydride revealed an N-linked carbohydrate moiety at the Asn18 residue. No O-linked carbohydrate was detected, as judged by the failure of asialo-CD59 to bind peanut agglutinin and by its resistance to digestion by O-glycanase. The apparent molecular mass of CD59 was reduced from 18-20 to 14 kDa upon complete digestion with N-glycanase, with no detectable proteolysis. N-glycanase digestion of CD59 was associated with an 88 +/- 4% loss of the complement-inhibitory activity of the protein, as assessed by its capacity to protect chicken erythrocytes from lysis by the human C5b-9 proteins. By contrast, no change in function was observed after digestion of CD59 with neuraminidase, under conditions that removed greater than 60% of [3H]sialic acid residues. Despite loss of functional activity after N-glycanase digestion, we detected no change in the capacity of the deglycosylated CD59 to incorporate into erythrocyte membranes or to bind specifically and with species selectivity to the C8 and C9 components of the membrane attack complex. In order to alter the branched-chain structure of the N-linked carbohydrate of CD59 without enzymatic digestion, Chinese hamster ovary (CHO) cells transfected with cDNA for human CD59 were grown in the alpha-mannosidase inhibitor, 1-deoxymannojirimycin, resulting in conversion of approximately 70% of the membrane glycoprotein to a high mannose. When grown in the presence of 1-deoxymannojirimycin, the C5b-9-inhibitory activity of CD59 expressed on the surface of the transfected CHO cells was reduced by an amount comparable to that observed for the N-glycanase digested protein. Taken together, these data suggest that normal glycosylation of Asn18 in CD59 is required for the normal expression of its complement-inhibitory activity on membrane surfaces, although these N-linked sugar residues do not contribute to CD59's affinity for the C8 and C9 components of the C5b-9 complex.
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Affiliation(s)
- H Ninomiya
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City
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Zhao J, Rollins SA, Maher SE, Bothwell AL, Sims PJ. Amplified gene expression in CD59-transfected Chinese hamster ovary cells confers protection against the membrane attack complex of human complement. J Biol Chem 1991; 266:13418-22. [PMID: 1712784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Protection against the pore-forming activity of the human C5b-9 proteins was conferred on a nonprimate cell by transfection with cDNA encoding the human complement regulatory protein CD59. CD59 was stably expressed in Chinese hamster ovary cells using the pFRSV mammalian expression vector. After cloning and selection, the transfected cells were maintained in media containing various concentrations of methotrexate, which induced surface expression of up to 4.2 x 10(6) molecules of CD59/cell. Phosphatidylinositol-specific phospholipase C removed greater than 95% of surface-expressed CD59 antigen, confirming that recombinant CD59 was tethered to the Chinese hamster ovary plasma membrane by a lipid anchor. The recombinant protein exhibited an apparent molecular mass of 21-24 kDa (versus 18-21 kDa for human erythrocyte CD59). After N-glycanase digestion, recombinant and erythrocyte CD59 comigrated with apparent molecular masses of 12-14 kDa, suggesting altered structure of asparagine-linked carbohydrate in recombinant versus erythrocyte CD59. The function of the recombinant protein was evaluated by changes in the sensitivity of the CD59 transfectants to the pore-forming activity of human C5b-9. Induction of cell-surface expression of CD59 antigen inhibited C5b-9 pore formation in a dose-dependent fashion. CD59 transfectants expressing greater than or equal to 1.2 x 10(6) molecules of CD59/cell were completely resistant to human serum complement. By contrast, CD59 transfectants remained sensitive to the pore-forming activity of guinea pig C8 and C9 (bound to human C5b67). Functionally blocking antibody against erythrocyte CD59 abolished the human complement resistance observed for the CD59-transfected Chinese hamster ovary cells. These results confirm that the C5b-9 inhibitory function of the human erythrocyte membrane is provided by CD59 and suggest that the gene for this protein can be expressed in xenotypic cells to confer protection against human serum complement.
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Affiliation(s)
- J Zhao
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Rollins SA, Zhao J, Ninomiya H, Sims PJ. Inhibition of homologous complement by CD59 is mediated by a species-selective recognition conferred through binding to C8 within C5b-8 or C9 within C5b-9. J Immunol 1991; 146:2345-51. [PMID: 1706395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The capacity of the human complement regulatory protein CD59 to interact with terminal complement proteins in a species-selective manner was examined. When incorporated into chicken E, CD59 (purified from human E membranes) inhibited the cytolytic activity of the C5b-9 complex in a manner dependent on the species of origin of C8 and C9. Inhibition of C5b-9-mediated hemolysis was maximal when C8 and C9 were derived from human (hu) or baboon serum. By contrast, CD59 showed reduced activity when C8 and C9 were derived from dog or sheep serum, and no activity when C8 and C9 were derived from either rabbit or guinea pig (gp) serum. Similar specificity on the basis of the species of origin of C8 and C9 was also observed for CD59 endogenous to the human E membrane, using functionally blocking antibody against this cell surface protein to selectively abrogate its C5b-9-inhibitory activity. When E bearing human CD59 were exposed to C5b-8hu, CD59 was found to inhibit C5b-9-mediated lysis, regardless of the species of origin of C9, suggesting that the inhibitory function of CD59 can be mediated through recognition of species-specific domains expressed by human C8. Consistent with this interpretation, CD59 was found to bind to C5b-8hu but not to C5b67hu or C5b67huC8gp. Although CD59 failed to inhibit hemolysis mediated by C5b67huC8gpC9gp, its inhibitory function was observed for C5b67huC8gpC9hu, suggesting that, in addition to its interaction with C5b-8hu, CD59 also interacts in a species-selective manner with C9hu incorporated into C5b-9. Consistent with this interpretation, CD59 was found to bind both C5b67huC8gpC9hu and C5b-8huC9gp, but not C5b67huC8gpC9gp. Taken together, these data suggest that the capacity of CD59 to restrict the hemolytic activity of human serum complement involves a species-selective interaction of CD59, which involves binding to both the C8 and C9 components of the membrane attack complex. Although CD59 expresses selectivity for C8 and C9 of human origin, this "homologous restriction" is not absolute, and this human complement regulatory protein retains functional activity toward C8 and C9 of some nonprimate species.
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Affiliation(s)
- S A Rollins
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Rollins SA, Zhao J, Ninomiya H, Sims PJ. Inhibition of homologous complement by CD59 is mediated by a species-selective recognition conferred through binding to C8 within C5b-8 or C9 within C5b-9. The Journal of Immunology 1991. [DOI: 10.4049/jimmunol.146.7.2345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Abstract
The capacity of the human complement regulatory protein CD59 to interact with terminal complement proteins in a species-selective manner was examined. When incorporated into chicken E, CD59 (purified from human E membranes) inhibited the cytolytic activity of the C5b-9 complex in a manner dependent on the species of origin of C8 and C9. Inhibition of C5b-9-mediated hemolysis was maximal when C8 and C9 were derived from human (hu) or baboon serum. By contrast, CD59 showed reduced activity when C8 and C9 were derived from dog or sheep serum, and no activity when C8 and C9 were derived from either rabbit or guinea pig (gp) serum. Similar specificity on the basis of the species of origin of C8 and C9 was also observed for CD59 endogenous to the human E membrane, using functionally blocking antibody against this cell surface protein to selectively abrogate its C5b-9-inhibitory activity. When E bearing human CD59 were exposed to C5b-8hu, CD59 was found to inhibit C5b-9-mediated lysis, regardless of the species of origin of C9, suggesting that the inhibitory function of CD59 can be mediated through recognition of species-specific domains expressed by human C8. Consistent with this interpretation, CD59 was found to bind to C5b-8hu but not to C5b67hu or C5b67huC8gp. Although CD59 failed to inhibit hemolysis mediated by C5b67huC8gpC9gp, its inhibitory function was observed for C5b67huC8gpC9hu, suggesting that, in addition to its interaction with C5b-8hu, CD59 also interacts in a species-selective manner with C9hu incorporated into C5b-9. Consistent with this interpretation, CD59 was found to bind both C5b67huC8gpC9hu and C5b-8huC9gp, but not C5b67huC8gpC9gp. Taken together, these data suggest that the capacity of CD59 to restrict the hemolytic activity of human serum complement involves a species-selective interaction of CD59, which involves binding to both the C8 and C9 components of the membrane attack complex. Although CD59 expresses selectivity for C8 and C9 of human origin, this "homologous restriction" is not absolute, and this human complement regulatory protein retains functional activity toward C8 and C9 of some nonprimate species.
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Affiliation(s)
- S A Rollins
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
| | - J Zhao
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
| | - H Ninomiya
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
| | - P J Sims
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Rollins SA, Sims PJ. The complement-inhibitory activity of CD59 resides in its capacity to block incorporation of C9 into membrane C5b-9. The Journal of Immunology 1990. [DOI: 10.4049/jimmunol.144.9.3478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Abstract
A human E membrane protein that inhibits lysis by the purified human C5b-9 proteins was isolated and characterized. After final purification, the protein migrated as an 18- to 20-kDa band by SDS-PAGE. Elution from gel slices and functional assay after SDS-PAGE (nonreduced) confirmed that all C5b-9 inhibitory activity of the purified protein resided in the 18- to 20-kDa band. Phosphatidylinositol-specific phospholipase C digestion of the purified protein abolished 50% of its C5b-9 inhibitory activity, and removed approximately 15% of the protein from human E. Western blots of normal and paroxysmal nocturnal hemoglobinuria E revealed an absence of the 18- to 20-kDa protein in the paroxysmal nocturnal hemoglobinuria E cells. The identity of this E protein with leukocyte Ag CD59 (P18, HRF20) was confirmed immunochemically and by N-terminal amino acid sequence analysis. A blocking antibody raised against the purified protein reacted with a single 18- to 20-kDa band on Western blots of human erythrocyte membranes. Prior incubation of human E with the F(ab) of this antibody increased subsequent lysis by the purified human C5b-9 proteins. Potentiation of C5b-9-mediated lysis was observed when erythrocytes were preincubated with this blocking antibody before C5b-9 assembly was initiated, or, when this antibody was added after 30 min, 0 degrees C incubation of C5b-8-treated E with C9. Chicken E incubated with purified CD59 were used to further characterize the mechanism of its C-inhibitory activity. Preincorporation of CD59 into these cells inhibited lysis by C5b-9, regardless of whether CD59 was added before or after assembly of the C5b-8 complex. When incorporated into the membrane, CD59 inhibited binding of 125I-C9 to membrane C5b-8 and reduced the extent of formation of SDS-resistant C9 polymer. The inhibitory effect of CD59 on 125I-C9 incorporation was most pronounced at near-saturating input of C9 (to C5b-8). By contrast, CD59 did not inhibit either C5b67 deposition onto the cell surface, or, binding of 125I-C8 to preassembled membrane C5b67. Taken together, these data suggest that CD59 exerts its C-inhibitory activity by limiting incorporation of multiple C9 into the membrane C5b-9 complex.
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Affiliation(s)
- S A Rollins
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
| | - P J Sims
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Rollins SA, Sims PJ. The complement-inhibitory activity of CD59 resides in its capacity to block incorporation of C9 into membrane C5b-9. J Immunol 1990; 144:3478-83. [PMID: 1691760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A human E membrane protein that inhibits lysis by the purified human C5b-9 proteins was isolated and characterized. After final purification, the protein migrated as an 18- to 20-kDa band by SDS-PAGE. Elution from gel slices and functional assay after SDS-PAGE (nonreduced) confirmed that all C5b-9 inhibitory activity of the purified protein resided in the 18- to 20-kDa band. Phosphatidylinositol-specific phospholipase C digestion of the purified protein abolished 50% of its C5b-9 inhibitory activity, and removed approximately 15% of the protein from human E. Western blots of normal and paroxysmal nocturnal hemoglobinuria E revealed an absence of the 18- to 20-kDa protein in the paroxysmal nocturnal hemoglobinuria E cells. The identity of this E protein with leukocyte Ag CD59 (P18, HRF20) was confirmed immunochemically and by N-terminal amino acid sequence analysis. A blocking antibody raised against the purified protein reacted with a single 18- to 20-kDa band on Western blots of human erythrocyte membranes. Prior incubation of human E with the F(ab) of this antibody increased subsequent lysis by the purified human C5b-9 proteins. Potentiation of C5b-9-mediated lysis was observed when erythrocytes were preincubated with this blocking antibody before C5b-9 assembly was initiated, or, when this antibody was added after 30 min, 0 degrees C incubation of C5b-8-treated E with C9. Chicken E incubated with purified CD59 were used to further characterize the mechanism of its C-inhibitory activity. Preincorporation of CD59 into these cells inhibited lysis by C5b-9, regardless of whether CD59 was added before or after assembly of the C5b-8 complex. When incorporated into the membrane, CD59 inhibited binding of 125I-C9 to membrane C5b-8 and reduced the extent of formation of SDS-resistant C9 polymer. The inhibitory effect of CD59 on 125I-C9 incorporation was most pronounced at near-saturating input of C9 (to C5b-8). By contrast, CD59 did not inhibit either C5b67 deposition onto the cell surface, or, binding of 125I-C8 to preassembled membrane C5b67. Taken together, these data suggest that CD59 exerts its C-inhibitory activity by limiting incorporation of multiple C9 into the membrane C5b-9 complex.
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Affiliation(s)
- S A Rollins
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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Sims PJ, Rollins SA, Wiedmer T. Regulatory control of complement on blood platelets. Modulation of platelet procoagulant responses by a membrane inhibitor of the C5b-9 complex. J Biol Chem 1989; 264:19228-35. [PMID: 2808422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Antibody against a membrane inhibitor of the C5b-9 complex has been used to investigate regulatory control of the terminal complement proteins on blood platelets. Monospecific rabbit antibody (alpha-P18) was raised against the purified 18-kDa erythrocyte membrane inhibitor of C5b-9 (Sugita, Y., Nakano, Y., and Tomita, M. (1988) J. Biochem. (Tokyo) 104, 633-637). In addition to its interaction with erythrocytes, this antibody (and its Fab) bound specifically to platelet membranes. In immunoblots of cell membrane proteins prepared under non-reducing conditions, alpha-P18 bound specifically to an 18-kDa erythrocyte membrane protein and to a 37-kDa platelet membrane protein. Absorption of this antibody by platelet membranes competed its binding to the purified 18-kDa erythrocyte protein, suggesting that epitopes expressed by the erythrocyte 18-kDa C5b-9 inhibitor are common to the platelet. When bound to the platelet surface, the Fab of alpha-P18 increased C9 activation by membrane C5b-8, monitored by exposure of a complex-dependent C9 neo-epitope. Although alpha-P18 caused little increase in the cytolysis of platelets treated with C5b-9 (total release of lactate dehydrogenase less than 5%), it markedly increased the cell stimulatory responses induced by these complement proteins, including, secretion from platelet alpha- and dense granules, conformational activation of cell surface GP IIb-IIIa, release of membrane microparticles from the platelet surface, and exposure of new membrane binding sites for components of the prothrombinase enzyme complex. Prior incubation of C5b67 platelets with 100 micrograms/ml alpha-P18 (Fab) lowered by approximately 10-fold the half-maximal concentration of C8 required to elicit each of these responses (in the presence of excess C9). Incubation with alpha-P18 (Fab) alone did not activate platelets, nor did incubation with this antibody potentiate the stimulatory responses of platelets exposed to other agonists. These data indicate that a membrane inhibitor of the C5b-9 complex normally serves to attenuate the procoagulant responses of blood platelets exposed to activated complement proteins, and suggest the mechanism by which a deletion or inactivation of this cell surface component would increase the risk of vascular thrombosis.
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Affiliation(s)
- P J Sims
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City 73104
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