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Lima M. Laboratory studies for paroxysmal nocturnal hemoglobinuria, with emphasis on flow cytometry. Pract Lab Med 2020; 20:e00158. [PMID: 32195308 PMCID: PMC7078534 DOI: 10.1016/j.plabm.2020.e00158] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Revised: 01/28/2020] [Accepted: 02/28/2020] [Indexed: 12/15/2022] Open
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare acquired clonal hematopoietic stem cell disorder caused by somatic mutations in the PIG-A gene, leading to the production of blood cells with absent or decreased expression of glycosylphosphatidylinositol-anchored proteins, including CD55 and CD59. Clinically, PNH is classified into three variants: classic (hemolytic), in the setting of another specified bone marrow disorder (such as aplastic anemia or myelodysplastic syndrome) and subclinical (asymptomatic). PNH testing is recommended for patients with intravascular hemolysis, acquired bone marrow failure syndromes and thrombosis with unusual features. Despite the availability of consensus guidelines for PNH diagnosis and monitoring, there are still discrepancies on how PNH tests are carried out, and these technical variations may lead to an incorrect diagnosis. Herein, we provide a brief historical overview of PNH, focusing on the laboratory tests available and on the current recommendations for PNH diagnosis and monitoring based in flow cytometry.
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Affiliation(s)
- Margarida Lima
- Laboratório de Citometria, Unidade de Diagnóstico Hematológico, Serviço de Hematologia Clínica, Hospital de Santo António (HSA), Centro Hospitalar Universitário do Porto (CHUP), Porto, Portugal
- Unidade Multidisciplinar de Investigação Biomédica, Instituto de Ciências Biomédicas da Universidade do Porto (UMIB/ICBAS/UP), Porto, Portugal
- Laboratório de Citometria, Hospital de Santo António (HSA), Centro Hospitalar Universitário do Porto (CHUP), Ex-CICAP, Rua D. Manuel II, s/n, 4099-001, Porto, Portugal.
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Morgan J, Spendlove I, Durrant LG. The role of CD55 in protecting the tumour environment from complement attack. TISSUE ANTIGENS 2002; 60:213-23. [PMID: 12445304 DOI: 10.1034/j.1399-0039.2002.600303.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
CD55 is a complement regulatory protein expressed by cells to protect them from bystander killing by complement. CD55 is over-expressed 2-100-fold on tumour cells and is deposited in large amounts within tumour matrix. Vascular endothelial growth factor (VEGF) produced by tumours to stimulate angiogenesis, also up-regulates endothelial cell surface expression of CD55 and stimulates the release of matrix degrading metalloproteinases. This study investigated the effects of VEGF on CD55 deposition into matrix and the release of CD55 by metalloproteinases. In contrast to inflammatory cytokines, CD55 was up-regulated by VEGF at the cell surface and within the extracellular matrix (ECM). Interestingly, human umbilical vein endothelial cells (HUVEC) exposed to VEGF released similar amounts of CD55 into the ECM as a tumour cell line expressing 50-fold higher level of CD55 on its cell surface. Furthermore, in contrast to earlier studies, both tumour and HUVEC-derived CD55 was functionally active. However, in contrast to papain that degrades CD55, and collagenase that fails to release CD55, MMP-7 released intact CD55 from ECM. This suggests that it may have a further role to play in protecting cells during inflammation and invasion.
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Affiliation(s)
- J Morgan
- The University of Nottingham, Cancer Research UK, Nottingham, UK
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Abstract
DAF is a GPI-anchored protein expressed on all blood cells and most other cell types. This complement regulatory protein functions intrinsically in cell membranes to protect host cells from autologous complement attack. A soluble form is found in body fluids. In human urine, two forms of DAF have been described. Here we report that these two forms correspond to soluble DAF and to DAF bound onto urinary vesicles. With a newly established, highly sensitive ELISA, the proportion of these two forms could be quantified in healthy individuals and patients having renal disorders. This ELISA allowed us to measure DAF on blood cells and also in plasma. In contrast to urine, human plasma contained only soluble DAF when the plasma was thoroughly depleted of platelets. The concentration of soluble DAF in human serum was always lower than in the corresponding plasma, suggesting that this form might adhere to the clot during the coagulation process.
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Affiliation(s)
- Sylvie Miot
- Department of Research, Immunonephrologie, Kantonsspital Basel, Hebelstrasse 20, 4031, Basel, Switzerland.
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4
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Abstract
CD55 is a protein that protects cells from complement-mediated attack. 791Tgp72 is an antigen which has been used successfully as a target for both tumour imaging and cancer vaccines. 791Tgp72 has recently been identified as CD55. Quantitative expression of CD55 in the tumour environment was therefore studied. Tumour cells showed a 4-100-fold increase in CD55 cell surface expression when compared to normal cells. Immunohistochemical staining of colorectal tumours also revealed high expression of CD55 in the stroma. To examine the source of this stromal CD55 the ability of both epithelial cells and endothelial cells to produce extracellular CD55 was measured. Tumour cell lines deposit CD55 into their extracellular matrix (ECM) in direct proportion to their cell surface expression. In contrast the ECM from HUVEC cells contained large amounts of CD55 despite expressing low levels of CD55 on their cell surface. Furthermore expression of CD55 on HUVEC cells was increased by exposure to VEGF. Although it remains unclear why CD55 is upregulated in the tumour environment its high level of expression on tumour cells and associated endothelium may explain why it is a good target for both imaging and immunotherapy.
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Affiliation(s)
- L Li
- CRC Academic Unit of Clinical Oncology, University of Nottingham, City Hospital, Hucknall Road, Nottingham, NG5 1PB, UK
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Brodsky RA, Mukhina GL, Li S, Nelson KL, Chiurazzi PL, Buckley JT, Borowitz MJ. Improved detection and characterization of paroxysmal nocturnal hemoglobinuria using fluorescent aerolysin. Am J Clin Pathol 2000; 114:459-66. [PMID: 10989647 PMCID: PMC4124633 DOI: 10.1093/ajcp/114.3.459] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is caused by a somatic mutation in the gene PIGA, which encodes an enzyme essential for the synthesis of glycosylphosphatidylinositol (GPI) anchors. The PIGA mutation results in absence or marked deficiency of more than a dozen proteins on PNH blood cells. Current flow cytometric assays for PNH rely on the use of labeled antibodies to detect deficiencies of specific GPI anchor proteins, such as CD59. However, because no single GPI anchor protein is always expressed in all cell lineages, no one monoclonal antibody can be used with confidence to diagnose PNH. We describe a new diagnostic test for PNH, based on the ability of a fluorescently labeled inactive variant of the protein aerolysin (FLAER) to bind selectively to GPI anchors. We compared GPI anchor protein expression in 8 patients with PNH using FLAER and anti-CD59. In all cases, FLAER detected similar or higher proportions of PNH monocytes and granulocytes compared with anti-CD59. Because of the increased sensitivity of detection, FLAER could detect small abnormal granulocyte populations in patients to a level of about 0.5%; samples from healthy control subjects contained substantially fewer FLAER-negative cells. FLAER gives a more accurate assessment of the GPI anchor deficit in PNH.
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Affiliation(s)
- R A Brodsky
- Department of Oncology, Johns Hopkins University, Baltimore, MD, USA
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Molecular Cloning and Characterization of Decay-Accelerating Factor Deficiency in Cromer Blood Group Inab Phenotype. Blood 1998. [DOI: 10.1182/blood.v91.2.680] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractAn additional decay-accelerating factor (DAF) mutation, designated as Inab phenotype in the Cromer blood group system, was recently identified in a 28-year-old Japanese woman (H.A.). The red blood cells of H.A., like those of other Inab phenotype individuals, were negative for Cromer system antigens, Cra, Tca, Dra, UMC, and IFC. The deficiency of DAF on the red blood cells of H.A. has been shown by immunoblotting with a murine monoclonal antibody to DAF. Molecular analysis has shown that H.A. is homozygous for a single nucleotide substitution, C1579→A, at the position 24 bp upstream of the 3′-end of exon 2 of the DAF gene. This substitution causes the activation of a novel cryptic splice site and results in the production of mRNA with a 26 bp deletion. The deletion introduces a reading frame shift and creates a stop codon immediately downstream of the deletion. Translation of mRNA would be terminated at the first amino acid residue of the second short consensus repeat (SCR2) domain (exon 3) of DAF. The functional domains of DAF's complement regulatory activity and the carboxy-terminal signal domains for glycosylphosphatidylinositol (GPI) anchoring are predicted to be lacking in H.A. Thus, there would be no DAF present on the cell surface.
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7
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Molecular Cloning and Characterization of Decay-Accelerating Factor Deficiency in Cromer Blood Group Inab Phenotype. Blood 1998. [DOI: 10.1182/blood.v91.2.680.680_680_684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An additional decay-accelerating factor (DAF) mutation, designated as Inab phenotype in the Cromer blood group system, was recently identified in a 28-year-old Japanese woman (H.A.). The red blood cells of H.A., like those of other Inab phenotype individuals, were negative for Cromer system antigens, Cra, Tca, Dra, UMC, and IFC. The deficiency of DAF on the red blood cells of H.A. has been shown by immunoblotting with a murine monoclonal antibody to DAF. Molecular analysis has shown that H.A. is homozygous for a single nucleotide substitution, C1579→A, at the position 24 bp upstream of the 3′-end of exon 2 of the DAF gene. This substitution causes the activation of a novel cryptic splice site and results in the production of mRNA with a 26 bp deletion. The deletion introduces a reading frame shift and creates a stop codon immediately downstream of the deletion. Translation of mRNA would be terminated at the first amino acid residue of the second short consensus repeat (SCR2) domain (exon 3) of DAF. The functional domains of DAF's complement regulatory activity and the carboxy-terminal signal domains for glycosylphosphatidylinositol (GPI) anchoring are predicted to be lacking in H.A. Thus, there would be no DAF present on the cell surface.
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Cozzi E, Tucker AW, Langford GA, Pino-Chavez G, Wright L, O'Connell MJ, Young VJ, Lancaster R, McLaughlin M, Hunt K, Bordin MC, White DJ. Characterization of pigs transgenic for human decay-accelerating factor. Transplantation 1997; 64:1383-92. [PMID: 9392299 DOI: 10.1097/00007890-199711270-00002] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND To prevent the central role played by complement activation in the hyperacute rejection of pig organs transplanted into primates, pigs transgenic for human decay-accelerating factor (HDAF) have recently been produced. The data presented here extend previous immunohistochemical findings by documenting the immunological characterization and the levels of expression of HDAF in these transgenic pigs. METHODS Animals from 30 independently derived lines were included in this study. HDAF expression was characterized by immunoprecipitation and epitope mapping. Quantitative analysis was performed by radiometric assays followed by Scatchard analysis and by double-determinant radioimmunoassay. Deposition of iC3b on porcine aortic endothelial cells was determined by radioimmunoassay. DNA slot-blot analysis and densitometric scanning were used to evaluate HDAF transgene copy number. RESULTS The integrity of HDAF expressed by these transgenic pigs could be demonstrated. HDAF was present in 72% of the organs analyzed, although considerable variation in expression occurred, both between animals and within the same pig. High levels of HDAF on porcine aortic endothelial cells resulted in iC3b deposition at levels as low as that detected on human endothelial cells. Twenty-six organs expressed levels of HDAF greater than those observed in the equivalent human tissue. HDAF expression did not correlate with the number of copies of the transgene incorporated into the porcine genome. CONCLUSIONS Transgenic pigs, which express levels of functional HDAF even greater than those observed in humans, have successfully been produced. Pigs transgenic for human complement inhibiting molecules could represent a source of organs for future clinical xenotransplantation.
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Affiliation(s)
- E Cozzi
- Department of Surgery, University of Cambridge, and Imutran Ltd. (A Novartis Pharma AG Company), England
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Kinoshita T. Protection of host from its own complement by membrane-bound complement inhibitors: C3 convertase inhibitors vs membrane attack complex inhibitors. RESEARCH IN IMMUNOLOGY 1996; 147:100-3. [PMID: 8792468 DOI: 10.1016/0923-2494(96)87181-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- T Kinoshita
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka, Japan
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Parsons SF, Mallinson G, Holmes CH, Houlihan JM, Simpson KL, Mawby WJ, Spurr NK, Warne D, Barclay AN, Anstee DJ. The Lutheran blood group glycoprotein, another member of the immunoglobulin superfamily, is widely expressed in human tissues and is developmentally regulated in human liver. Proc Natl Acad Sci U S A 1995; 92:5496-500. [PMID: 7777537 PMCID: PMC41722 DOI: 10.1073/pnas.92.12.5496] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Glycoproteins expressing the Lutheran blood group antigens were isolated from human erythrocyte membranes and from human fetal liver. Amino acid sequence analyses allowed the design of redundant oligonucleotides that were used to generate a 459-bp, sequence-specific probe by PCR. A cDNA clone of 2400 bp was isolated from a human placental lambda gt 11 library and sequenced, and the deduced amino acid sequence was studied. The predicted mature protein is a type I membrane protein of 597 amino acids with five potential N-glycosylation sites. There are five disulfide-bonded, extracellular, immunoglobulin superfamily domains (two variable-region set and three constant-region set), a single hydrophobic, membrane-spanning domain, and a cytoplasmic domain of 59 residues. The overall structure is similar to that of the human tumor marker MUC 18 and the chicken neural adhesion molecule SC1. The extracellular domains and cytoplasmic domain contain consensus motifs for the binding of integrin and Src homology 3 domains, respectively, suggesting possible receptor and signal-transduction function. Immunostaining of human tissues demonstrated a wide distribution and provided evidence that the glycoprotein is under developmental control in liver and may also be regulated during differentiation in other tissues.
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Affiliation(s)
- S F Parsons
- International Blood Group Reference Laboratory, Bristol, United Kingdom
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Morgan BP, Meri S. Membrane proteins that protect against complement lysis. SPRINGER SEMINARS IN IMMUNOPATHOLOGY 1994; 15:369-96. [PMID: 8153873 DOI: 10.1007/bf01837366] [Citation(s) in RCA: 174] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Affiliation(s)
- B P Morgan
- Department of Medical Biochemistry, University of Wales College of Medicine, Heath Park, Cardiff, UK
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Kalli KR, Hsu P, Fearon DT. Therapeutic uses of recombinant complement protein inhibitors. SPRINGER SEMINARS IN IMMUNOPATHOLOGY 1994; 15:417-31. [PMID: 8153875 PMCID: PMC7101590 DOI: 10.1007/bf01837368] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
In conclusion, it is apparent that researchers are poised at the threshold of developing inhibitors of complement activation from the molecules in the RCA family. By creating soluble forms of these protective proteins for in vivo administration, or by making transgenic animals expressing these proteins or their derivatives, it may be possible to inhibit complement-mediated pathology stemming from autoimmune disease, reperfusion injuries, and physical trauma. This technology combined with current attempts to protect allografts from cellular rejection with monoclonal antibodies against members of the integrin family of adhesion molecules [52] makes it possible that the excessive mortality due to the severe shortage of human donor organs could be overcome by the use of xenografts.
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Affiliation(s)
- K R Kalli
- Graduate Program in Immunology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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Spring FA. Characterization of blood-group-active erythrocyte membrane glycoproteins with human antiseras*. Transfus Med 1993. [DOI: 10.1111/j.1365-3148.1993.tb00112.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Holmes CH, Simpson KL. Complement and pregnancy: new insights into the immunobiology of the fetomaternal relationship. BAILLIERE'S CLINICAL OBSTETRICS AND GYNAECOLOGY 1992; 6:439-60. [PMID: 1446417 DOI: 10.1016/s0950-3552(05)80005-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recent studies have revealed that human trophoblast expresses three membrane-bound proteins which function specifically to regulate the activity of complement. These proteins are already known to be widely distributed in normal adult tissues where they protect host cells from damage resulting from the fortuitous deposition of activated complement components. Their activities are focused at two distinct steps in the complement pathway. Decay accelerating factor (DAF, CD55) and membrane co-factor protein (MCP, CD46) act at the level of the C3 convertase enzymes which activate C3 to C3b. A further protein, CD59, directly regulates the formation and function of the terminal cytolytic membrane attack complex (MAC) by specifically interacting with C8 and C9. These proteins appear to play an important role in the maintenance of normal human pregnancy. DAF, MCP and CD59 are all expressed where trophoblast surfaces are in contact with maternal blood and tissues and expression occurs from at least 6 weeks of gestation. The semi-allogeneic human conceptus therefore appears to be effectively protected from maternal complement-mediated damage arising either from alternative or classical pathway activation or in a bystander fashion following a response to microbial infection in the mother. Complement regulatory protein deficiency disorders with clinically demonstrable consequences especially in terms of haemolytic disease are known to exist and have proved valuable in establishing the biological role of these proteins in vivo. The demonstration of this new family of immunoregulatory proteins on trophoblast raises important questions about the potential involvement of these products in pregnancy pathologies.
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Affiliation(s)
- C H Holmes
- University of Bristol, Department of Obstetrics and Gynaecology, St Michael's Hospital, UK
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Hughes-Jones NC, Parsons SF. Monoclonal antibodies to red cell alloantigens with particular reference to anti-D. Transfus Med Rev 1992; 6:191-200. [PMID: 1498464 DOI: 10.1016/s0887-7963(92)70169-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- N C Hughes-Jones
- MRC Molecular Immunopathology Unit, MRC Centre, Cambridge, England
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Fletcher A, Bryant JA, Gardner B, Judson PA, Spring FA, Parsons SF, Mallinson G, Anstee DJ. New monoclonal antibodies in CD59: use for the analysis of peripheral blood cells from paroxysmal nocturnal haemoglobinuria (PNH) patients and for the quantitation of CD59 on normal and decay accelerating factor (DAF)-deficient erythrocytes. Immunol Suppl 1992; 75:507-12. [PMID: 1374058 PMCID: PMC1384747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
CD59 is a widely expressed cell surface glycosylphosphatidylinositol (GPI)-linked glycoprotein which acts as an inhibitor of the assembly of the membrane attack complex of autologous complement. Four new monoclonal antibodies to CD59 (2/24, 1B2, BRIC 229, BRIC 257) are described. Competitive binding experiments using these antibodies, two known CD59 antibodies (MEM-43, YTH 53.1) and a previously described antibody LICR-LON-Fib75.1 demonstrated that all seven antibodies see related epitopes on human erythrocyte CD59. In common with other GPI-linked proteins, CD59 (as defined by antibody 2/24) was sensitive to treatment with phosphatidylinositol-specific phospholipase C (PI-PLC) on lymphocytes and monocytes but not on erythrocytes. Flow cytometric analysis using antibody 2/24 identified two populations (CD59 positive and CD59 deficient) of lymphocytes, monocytes and erythrocytes in peripheral blood from a patient with paroxysmal nocturnal haemoglobinuria (PNH). The abundance of CD59 on normal erythrocytes was determined as 21,000 copies/cell when radioiodinated BRIC 229 was used. Other CD59 antibodies gave values of 10,000 (IF5) and 15,000 (2/24) against the same target cells. Radioiodinated Fab fragments of BRIC 229 gave a value of 39,000 copies/cell. Erythrocytes from two individuals with a rare inherited deficiency of decay accelerating factor (DAF), known as the Inab phenotype, expressed normal levels of CD59.
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Affiliation(s)
- A Fletcher
- Australian Red Cross Society, New South Wales Division, Blood Transfusion Service, Sydney
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Telen MJ, Rosse WF. Phosphatidylinositol-glycan linked proteins of the erythrocyte membrane. BAILLIERE'S CLINICAL HAEMATOLOGY 1991; 4:849-68. [PMID: 1724205 DOI: 10.1016/s0950-3536(06)80033-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The human erythrocyte bears a number of proteins anchored to the outer membrane surface via a phosphatidylinositol-glycan linkage. This class of proteins includes several complement regulatory proteins (including decay-accelerating factor, CD59 antigen (protectin), and C8 binding protein) as well as several enzymes and at least one protein important in cell-cell interaction. In addition, a number of blood group antigens have been identified to reside on proteins with phosphatidylinositol anchors. One blood group (Cromer) resides on DAF. Study of variants in this blood group system has led to interesting information about the function and expression of this protein. Several other blood groups, such as JMH and Holley/Gregory, appear to reside on as yet unidentified phosphatidylinositol-linked proteins. In paroxysmal nocturnal haemoglobinuria, a variable proportion of red cells fail to express or express weakly all phosphatidylinositol-linked proteins. The origin of this deficiency is now being worked out. In addition, individuals with inherited deficiency of DAF or CD59 (protectin) have been identified. Only the latter deficiency leads to a PNH-like syndrome.
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Spring FA, Reid ME. Evidence that the human blood group antigens Gya and Hy are carried on a novel glycosylphosphatidylinositol-linked erythrocyte membrane glycoprotein. Vox Sang 1991; 60:53-9. [PMID: 1828922 DOI: 10.1111/j.1423-0410.1991.tb00871.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Immunoblotting under non-reducing conditions with purified human anti-Gya and anti-Hy locates both antigens to an erythrocyte membrane glycoprotein of apparent Mr 46,750-57,500. The antigens are destroyed on intact red cells by the enzymes pronase, trypsin and chymotrypsin, and by treatment with reducing agents. Immunoblotting with anti-Gya and anti-Hy to membranes prepared from red cells pre-treated with an Endo F preparation caused a mean reduction in apparent Mr of the glycoprotein by 11 kDa at the leading and trailing edges, when compared with control membranes. These results suggest that the glycoprotein has one or more complex N-glycans that are not completely sensitive to Endo F digestion on intact cells. The majority of Gya/Hy-active molecules are not tightly associated with the red cell membrane skeleton. A gross reduction in reactivity with anti-Gya and anti-Hy by immunoblotting was observed in red cell membranes from patients with paroxysmal nocturnal haemoglobinuria, suggesting a possible membrane linkage via glycosylphosphatidylinositol for the glycoprotein that carries the Gya and Hy antigens. Immunoprecipitation of the glycoprotein by anti-Gya showed that the protein migrates faster under reducing conditions (Mr 45,000-54,000). A putative dimer was also evident in the precipitates. The glycoprotein was demonstrated to be distinct from lymphocyte-function-associated antigen-3 (CD58), the LWab-active glycoprotein, the Fya-active glycoprotein, the Oka-active glycoprotein and the BRIC 125 glycoprotein (CD47).
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Affiliation(s)
- F A Spring
- South Western Regional Transfusion Centre, Bristol, UK
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Spring FA, Herron R, Rowe G. An erythrocyte glycoprotein of apparent Mr 60,000 expresses the Sc1 and Sc2 antigens. Vox Sang 1990; 58:122-5. [PMID: 2339520 DOI: 10.1111/j.1423-0410.1990.tb02074.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Immunoblotting with human anti-Sc1 and anti-Sc2 locates the Sc1 and Sc2 antigens to an erythrocyte membrane glycoprotein of apparent Mr 60,000. The antigens are destroyed by pronase, and require intact disulphide bonds for expression. A proportion of the molecules carrying the Sc1 and Sc2 antigens are associated with red cell cytoskeleton preparations. Treatment of intact cells with an Endo F preparation resulted in the loss of the Sc2 antigen but not the Sc1 antigen, suggesting that the Sc2 antigen is dependent on the presence of one or more complex N-glycans for its expression.
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Affiliation(s)
- F A Spring
- South Western Regional Blood Transfusion Centre, Southmead, Bristol, UK
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Abstract
The surface of the human red blood cell is dominated by a small number of abundant blood group active proteins. The major proteins are the anion transport protein (band 3) which has AB(H) activity, and Glycophorin A which has MN activity. Band 3 and Glycophorin A are of equal abundance in the normal red cell membrane (approximately 10(6) copies of each) and the two proteins may associate together as a complex. The glucose transporter (band 4.5) had AB(H) activity and there are about 5 x 10(5) copies/red cell. Several polypeptides associate together to form the Rh complex. The major components of this complex (abundance 1-2 x 10(5) copies/red cell) are polypeptides of Mr 30,000, polypeptides of Mr 45,000-100,000 and Glycophorin B. The antigens of the Rh blood group system appear to be associated with the polypeptides of Mr 30,000 and those of Mr 45,000-100,000 (the latter also express AB(H) activity). Glycophorin B expresses the blood group 'N' antigen and the Ss antigens. Glycophorins C and D carry the Gerbich antigens and, together, these polypeptides comprise approximately 10(5) copies/red cell. The complete protein sequence of all the above-mentioned proteins is known, except for the Mr 30,000 and Mr 45,000-100,000 polypeptides of the Rh complex for which only partial sequences are available, and Glycophorin D, the sequence of which can be inferred from that of Glycophorin C. Several of the minor blood group active proteins at the red cell surface (abundance less than 1.2 x 10(4)/red cell) have been the subject of recent studies. The polypeptide expressing Cromer-related blood group antigens has been identified as decay-accelerating factor and that carrying the Ina/Inb antigens as CD44. The protein sequence of both of these proteins has been deduced form nucleotide sequencing. The polypeptides expressing Kell antigens, Lutheran antigens, Fy antigens, and LW antigens have also been identified and partially characterised.
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Affiliation(s)
- D J Anstee
- Blood Group Reference Laboratory, South Western Regional Blood Transfusion Centre, Southmead, Bristol, UK
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