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Vayne C, Rollin J, Clare R, Daka M, Atsouawe M, Guéry EA, Cauchie P, Cordonnier C, Cuisenier P, De Maistre E, Donnard M, Drillaud N, Faille D, Galinat H, Gouin-Thibault I, Lemoine S, Mourey G, Mullier F, Siguret V, Susen S, Godon A, Nazy I, Gruel Y, Pouplard C. The use of 1E12, a monoclonal anti-platelet factor 4 antibody, to improve the diagnosis of vaccine-induced immune thrombotic thrombocytopenia. J Thromb Haemost 2024; 22:2306-2315. [PMID: 38762021 DOI: 10.1016/j.jtha.2024.05.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 04/04/2024] [Accepted: 05/02/2024] [Indexed: 05/20/2024]
Abstract
BACKGROUND Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a complication of adenoviral-based vaccine against SARS-CoV-2 due to prothrombotic immunoglobulin (Ig) G antibodies to platelet factor 4 (PF4) and may be difficult to distinguish from heparin-induced thrombocytopenia (HIT) in patients treated with heparin. OBJECTIVES We assessed the usefulness of competitive anti-PF4 enzyme immunoassays (EIAs) in this context. METHODS The ability of F(ab')2 fragments of 1E12, 1C12, and 2E1, 3 monoclonal anti-PF4 antibodies, to inhibit the binding of human VITT or HIT antibodies to PF4 was evaluated using EIAs. Alanine-scanning mutagenesis was performed to define the amino acids involved in the interactions between the monoclonal antibodies and PF4. RESULTS A strong inhibition of VITT IgG binding to PF4 was measured with 1E12 (median inhibition, 93%; n = 8), whereas it had no effect on the binding of HIT antibodies (median, 6%; n = 8). In contrast, 1C12 and 2E1 inhibited VITT (median, 74% and 76%, respectively) and HIT antibodies (median, 68% and 53%, respectively) binding to PF4. When a competitive anti-PF4 EIA was performed with 1E12 for 19 additional VITT samples, it strongly inhibited IgG binding to PF4, except for 1 patient, who had actually developed HIT according to the clinical history. Epitope mapping showed that 1E12 interacts with 5 key amino acids on PF4, of which 4 are also required for the binding of human VITT antibodies, thus explaining the competitive inhibition. CONCLUSION A simple competitive anti-PF4 EIA with 1E12 could help confirm VITT diagnosis and distinguish it from HIT in patients when both diagnoses are possible.
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MESH Headings
- Humans
- Platelet Factor 4/immunology
- Heparin/adverse effects
- Heparin/immunology
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/adverse effects
- COVID-19 Vaccines/adverse effects
- COVID-19 Vaccines/immunology
- Immunoglobulin G/blood
- Immunoglobulin G/immunology
- Predictive Value of Tests
- Anticoagulants/adverse effects
- Anticoagulants/immunology
- COVID-19/immunology
- COVID-19/prevention & control
- COVID-19/diagnosis
- Immunoglobulin Fab Fragments/immunology
- Immunoglobulin Fab Fragments/adverse effects
- Protein Binding
- Purpura, Thrombocytopenic, Idiopathic/immunology
- Purpura, Thrombocytopenic, Idiopathic/diagnosis
- Purpura, Thrombocytopenic, Idiopathic/chemically induced
- SARS-CoV-2/immunology
- Binding, Competitive
- Purpura, Thrombotic Thrombocytopenic/immunology
- Purpura, Thrombotic Thrombocytopenic/diagnosis
- Purpura, Thrombotic Thrombocytopenic/blood
- Purpura, Thrombotic Thrombocytopenic/chemically induced
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Affiliation(s)
- Caroline Vayne
- Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France; Institut National de la Santé et de la Recherche Médicale INSERM U1327 ISCHEMIA, Membrane Signalling and Inflammation in Reperfusion Injuries, Université de Tours, Tours, France.
| | - Jérôme Rollin
- Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France; Institut National de la Santé et de la Recherche Médicale INSERM U1327 ISCHEMIA, Membrane Signalling and Inflammation in Reperfusion Injuries, Université de Tours, Tours, France
| | - Rumi Clare
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Michael G. DeGroote Centre for Transfusion Research, Hamilton, Ontario, Canada
| | - Mercy Daka
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Michael G. DeGroote Centre for Transfusion Research, Hamilton, Ontario, Canada
| | - Merveille Atsouawe
- Institut National de la Santé et de la Recherche Médicale INSERM U1327 ISCHEMIA, Membrane Signalling and Inflammation in Reperfusion Injuries, Université de Tours, Tours, France
| | - Eve-Anne Guéry
- Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France
| | - Philippe Cauchie
- Service de Biologie Clinique, Centre Hospitalier Universitaire de Charleroi, Charleroi, Belgium
| | - Charlotte Cordonnier
- Inserm, Centre Hospitalier Universitaire Lille, U1172-Lille Neurosciences and Cognition, University of Lille, Lille, France
| | - Pauline Cuisenier
- Stroke Unit, Neurology Department, University Hospital of Grenoble Alpes, Grenoble, France
| | | | - Magali Donnard
- Haemostasis Unit, Limoges University Hospital, Limoges, France
| | - Nicolas Drillaud
- Department of Haemostasis, Nantes University Hospital, Nantes, France
| | - Dorothée Faille
- Département d'Hématologie Biologique, Institut National de la Santé et de la Recherche Médicale U1148, Laboratory for Vascular Translational Science, Centre Hospitalier Universitaire Bichat-Claude Bernard, Paris, France
| | - Hubert Galinat
- Service d'Hématologie Biologique, Centre Hospitalier Régional Universitaire Brest, Brest, France
| | - Isabelle Gouin-Thibault
- Department of Hemostasis, University Hospital of Rennes, Institut National de la Santé et de la Recherche Médicale, Ecole des Hautes Etudes en Santé Publique, Institut de Recherche en Santé, Environnement et Travail, Unité Mixte de Recherche_S 1085, University of Rennes, Rennes, France
| | - Sandrine Lemoine
- Centre Hospitalier Universitaire Angers, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Centre de Recherche en Cancérologie et Immunologie Intégrée Nantes Angers, Laboratoire d'Hématologie, Université d'Angers, Nantes Université, Angers, France
| | - Guillaume Mourey
- Service d'Hémostase, Centre Hospitalier Universitaire Besançon, Besançon, France
| | - François Mullier
- Université Catholique de Louvain Namur, Thrombosis and Hemostasis Center, Université catholique de Louvain, Centre Hospitalier Universitaire, Yvoir, Belgium
| | - Virginie Siguret
- Service d'Hématologie biologique, Hôpital Lariboisière, Institut National de la Santé et de la Recherche Médicale Unité Mixte de Recherche_S1140, Innovative Therapeutics in Haemostasis, University of Paris, Paris, France
| | - Sophie Susen
- Institut National de la Santé et de la Recherche Médicale, Centre Hospitalier Universitaire Lille, University of Lille, Institut Pasteur de Lille, U1011-Europena Genomic Institute for Diabetes, Lille, France
| | - Alban Godon
- Centre Hospitalier Universitaire Angers, Institut National de la Santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, Centre de Recherche en Cancérologie et Immunologie Intégrée Nantes Angers, Laboratoire d'Hématologie, Université d'Angers, Nantes Université, Angers, France
| | - Ishac Nazy
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada; Michael G. DeGroote Centre for Transfusion Research, Hamilton, Ontario, Canada; Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Yves Gruel
- Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France; Institut National de la Santé et de la Recherche Médicale INSERM U1327 ISCHEMIA, Membrane Signalling and Inflammation in Reperfusion Injuries, Université de Tours, Tours, France
| | - Claire Pouplard
- Department of Haemostasis, Regional University Hospital Centre Tours, Tours, France; Institut National de la Santé et de la Recherche Médicale INSERM U1327 ISCHEMIA, Membrane Signalling and Inflammation in Reperfusion Injuries, Université de Tours, Tours, France
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2
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Buka RJ, Montague SJ, Moran LA, Martin EM, Slater A, Watson SP, Nicolson PLR. PF4 activates the c-Mpl-Jak2 pathway in platelets. Blood 2024; 143:64-69. [PMID: 37883794 PMCID: PMC10862235 DOI: 10.1182/blood.2023020872] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/03/2023] [Accepted: 08/22/2023] [Indexed: 10/28/2023] Open
Abstract
ABSTRACT Platelet factor 4 (PF4) is an abundant chemokine that is released from platelet α-granules on activation. PF4 is central to the pathophysiology of vaccine-induced immune thrombocytopenia and thrombosis (VITT) in which antibodies to PF4 form immune complexes with PF4, which activate platelets and neutrophils through Fc receptors. In this study, we show that PF4 binds and activates the thrombopoietin receptor, cellular myeloproliferative leukemia protein (c-Mpl), on platelets. This leads to the activation of Janus kinase 2 (JAK2) and phosphorylation of signal transducer and activator of transcription (STAT) 3 and STAT5, leading to platelet aggregation. Inhibition of the c-Mpl-JAK2 pathway inhibits platelet aggregation to PF4, VITT sera, and the combination of PF4 and IgG isolated from VITT patient plasma. The results support a model in which PF4-based immune complexes activate platelets through binding of the Fc domain to FcγRIIA and PF4 to c-Mpl.
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Affiliation(s)
- Richard J. Buka
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Samantha J. Montague
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, Birmingham and Nottingham, United Kingdom
| | - Luis A. Moran
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Eleyna M. Martin
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, Birmingham and Nottingham, United Kingdom
| | - Alexandre Slater
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, Birmingham and Nottingham, United Kingdom
| | - Steve P. Watson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Centre of Membrane Proteins and Receptors, Universities of Birmingham and Nottingham, Birmingham and Nottingham, United Kingdom
| | - Phillip L. R. Nicolson
- Institute of Cardiovascular Sciences, College of Medical and Dental Sciences, University of Birmingham, Birmingham, United Kingdom
- Department of Haematology, University Hospitals Birmingham National Health Service Foundation Trust, Birmingham, United Kingdom
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3
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Schönborn L, Esteban O, Wesche J, Dobosz P, Broto M, Puig SR, Fuhrmann J, Torres R, Serra J, Llevadot R, Palicio M, Wang JJ, Gordon TP, Lindhoff-Last E, Hoffmann T, Alberio L, Langer F, Boehme C, Biguzzi E, Grosse L, Endres M, Liman T, Thiele T, Warkentin TE, Greinacher A. Anti-PF4 immunothrombosis without proximate heparin or adenovirus vector vaccine exposure. Blood 2023; 142:2305-2314. [PMID: 37883798 PMCID: PMC10862238 DOI: 10.1182/blood.2023022136] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 09/28/2023] [Accepted: 10/11/2023] [Indexed: 10/28/2023] Open
Abstract
ABSTRACT Platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies and anti-PF4 antibodies cause heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombocytopenia and thrombosis (VITT), respectively. Diagnostic and treatment considerations differ somewhat between HIT and VITT. We identified patients with thrombocytopenia and thrombosis without proximate heparin exposure or adenovirus-based vaccination who tested strongly positive by PF4/polyanion enzyme-immunoassays and negative/weakly positive by heparin-induced platelet activation (HIPA) test but strongly positive by PF4-induced platelet activation (PIPA) test (ie, VITT-like profile). We tested these patients by a standard chemiluminescence assay that detects anti-PF4/heparin antibodies found in HIT (HemosIL AcuStar HIT-IgG(PF4-H)) as well as a novel chemiluminescence assay for anti-PF4 antibodies found in VITT. Representative control sera included an exploratory anti-PF4 antibody-positive but HIPA-negative/weak cohort obtained before 2020 (n = 188). We identified 9 patients with a clinical-pathological profile of a VITT-like disorder in the absence of proximate heparin or vaccination, with a high frequency of stroke (arterial, n = 3; cerebral venous sinus thrombosis, n = 4), thrombocytopenia (median platelet count nadir, 49 × 109/L), and hypercoagulability (greatly elevated D-dimer levels). VITT-like serological features included strong reactivity by PIPA (aggregation <10 minutes in 9/9 sera) and positive testing in the novel anti-PF4 chemiluminescence assay (3/9 also tested positive in the anti-PF4/heparin chemiluminescence assay). Our exploratory cohort identified 13 additional patient sera obtained before 2020 with VITT-like anti-PF4 antibodies. Platelet-activating VITT-like anti-PF4 antibodies should be considered in patients with thrombocytopenia, thrombosis, and very high D-dimer levels, even without a proximate exposure to heparin or adenovirus vector vaccines.
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Affiliation(s)
- Linda Schönborn
- Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | | | - Jan Wesche
- Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | | | | | | | - Jessica Fuhrmann
- Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | | | | | | | | | - Jing Jing Wang
- Department of Immunology, College of Medicine and Public Health, Flinders University and SA Pathology, Bedford Park, SA, Australia
| | - Tom Paul Gordon
- Department of Immunology, College of Medicine and Public Health, Flinders University and SA Pathology, Bedford Park, SA, Australia
| | - Edelgard Lindhoff-Last
- Cardioangiology Center Bethanien Hospital, CCB Coagulation Center and CCB Coagulation Research Center, Frankfurt, Hessen, Germany
| | - Till Hoffmann
- Institute for Transplantation Diagnostics and Cell Therapeutics, University Hospital Duesseldorf, Medical Faculty, Duesseldorf, Germany
| | - Lorenzo Alberio
- Service and Central Laboratory of Hematology, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Florian Langer
- Zentrum für Onkologie, II. Medizinische Klinik und Poliklinik, Universitätsklinikum Eppendorf, Hamburg, Germany
| | - Christian Boehme
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Eugenia Biguzzi
- Clinic of Hematology, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland
| | - Leonie Grosse
- Department of Pediatrics, Dr. von Hauner Children’s Hospital, Ludwig Maximilian University, Munich, Germany
| | - Matthias Endres
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany
- Center for Stroke Research Berlin, Berlin, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Partner site Berlin, Berlin, Germany
- Deutsches Zentrum für Herz-Kreislauf-Forschung, Partner site Berlin, Berlin, Germany
| | - Thomas Liman
- Center for Stroke Research Berlin, Berlin, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen, Partner site Berlin, Berlin, Germany
- Department of Neurology, Evangelical Hospital Oldenburg, Carl von Ossietzky University, Oldenburg, Germany
| | - Thomas Thiele
- Institut für Transfusionsmedizin, Universitätsmedizin Rostock, Rostock, Germany
| | - Theodore E. Warkentin
- Department of Pathology and Molecular Medicine and Department of Medicine, McMaster University, Hamilton, ON, Canada
| | - Andreas Greinacher
- Institut für Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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4
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Warkentin TE, Greinacher A. Laboratory Testing for Heparin-Induced Thrombocytopenia and Vaccine-Induced Immune Thrombotic Thrombocytopenia Antibodies: A Narrative Review. Semin Thromb Hemost 2023; 49:621-633. [PMID: 36455619 PMCID: PMC10421650 DOI: 10.1055/s-0042-1758818] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) and vaccine-induced immune thrombotic thrombocytopenia (VITT) are highly prothrombotic (thrombosis frequency ≥50%). Both are caused by platelet-activating anti-platelet factor 4 (PF4) antibodies, forming PF4/IgG-containing immune complexes that engage platelet FcγIIa receptors, producing strong platelet activation. In HIT, heparin crosslinks several PF4 molecules, whereas in VITT, anti-PF4 antibodies alone crosslink PF4. Sufficient levels of circulating anti-PF4 antibodies are needed to create the pathogenic immune complexes on platelet surfaces; this explains why certain serum (plasma)-based assays are highly sensitive for detecting HIT/VITT antibodies. Accordingly, HIT and VITT are "clinical-pathological" disorders, that is, positive testing for such antibodies-together with a compatible clinical picture-is integral for diagnosis. Heparin (low concentrations) enhances HIT antibody-induced platelet activation, but platelet activation by VITT sera is usually inhibited by heparin. For both HIT and VITT, high sensitivity (>99% and >95%, respectively) characterizes PF4-dependent enzyme immunoassays (EIAs) and PF4-enhanced platelet activation assays; in contrast, certain rapid immunoassays have high sensitivity for HIT (>90-97%) but poor sensitivity (<25%) for VITT. HIT and VITT antibodies are directed at distinct sites on PF4: solid-phase EIAs and platelet activation assays are indifferent to these distinct antigen targets, but rapid immunoassays are not. We discuss a conceptual model where PF4 is viewed as a "globe," with the heparin-binding site the "equator"; in this model, HIT antibodies are primarily directed at antigen site(s) at the north and south "poles" of PF4 (formed when PF4 binds to heparin), whereas VITT antibodies recognize sites on the equator.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, Ontario, Canada
- Service of Benign Hematology, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada
| | - Andreas Greinacher
- Institute for Transfusion Medicine, University Medicine Greifswald, Greifswald, Germany
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5
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Zhu W, Zheng Y, Yu M, Wu Y, Wei J, Zhou L, Fu G, Schneider N, Jones C, Irani M, Padmanabhan A, Aster R, Wang D, Wen R. Cloned antibodies from patients with HIT provide new clues to HIT pathogenesis. Blood 2023; 141:1060-1069. [PMID: 36493339 PMCID: PMC10023725 DOI: 10.1182/blood.2022017612] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 11/01/2022] [Accepted: 11/17/2022] [Indexed: 12/14/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a serious adverse drug reaction characterized by antibodies that recognize platelet factor 4/heparin complexes (PF4/H) and activate platelets to create a prothrombotic state. Although a high percentage of heparin-treated patients produce antibodies to PF4/H, only a subset also makes antibodies that are platelet activating (PA). A close correlation between PA antibodies and the likelihood of experiencing HIT has been demonstrated in clinical studies, but how PA (presumptively pathogenic) and nonactivating (NA) (presumptively benign) antibodies differ from each other at the molecular level is unknown. To address this issue, we cloned 7 PA and 47 NA PF4/H-binding antibodies from 6 patients with HIT and characterized their structural and functional properties. Findings showed that PA clones differed significantly from NA clones in possessing 1 of 2 heavy chain complementarity-determining region 3 (HCDR3) motifs, RX1-2R/KX1-2R/H (RKH) and YYYYY (Y5), in an unusually long complementarity-determining region 3 (≥20 residues). Mutagenic studies showed that modification of either motif in PA clones reduced or abolished their PA activity and that appropriate amino acid substitutions in HCDR3 of NA clones can cause them to become PA. Repertoire sequencing showed that the frequency of peripheral blood IgG+ B cells possessing RKH or Y5 was significantly higher in patients with HIT than in patients without HIT given heparin, indicating expansion of B cells possessing RKH or Y5 in HIT. These findings imply that antibodies possessing RKH or Y5 are relevant to HIT pathogenesis and suggest new approaches to diagnosis and treatment of this condition.
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Affiliation(s)
- Wen Zhu
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | | | - Mei Yu
- Versiti Blood Research Institute, Milwaukee, WI
| | - Yaling Wu
- Versiti Blood Research Institute, Milwaukee, WI
- Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, China
| | - Jianhui Wei
- Versiti Blood Research Institute, Milwaukee, WI
- Biomedical Research Center of South China, College of Life Sciences, Fujian Normal University, Fuzhou, Fujian, China
| | - Lu Zhou
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | - Guoping Fu
- Versiti Blood Research Institute, Milwaukee, WI
| | | | | | - Mehraboon Irani
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Pathology, Medical College of Wisconsin, Milwaukee, WI
| | - Anand Padmanabhan
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Laboratory Medicine & Pathology, Mayo Clinic, Rochester, MN
| | - Richard Aster
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
| | - Demin Wang
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
| | - Renren Wen
- Versiti Blood Research Institute, Milwaukee, WI
- Department of Microbiology & Immunology, Medical College of Wisconsin, Milwaukee, WI
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Rollin J, Charuel N, Gruel Y, Billy S, Guéry E, May M, Pouplard C, Vayne C. Variable serotonin release assay pattern and specificity of PF4-specific antibodies in HIT, and clinical relevance. J Thromb Haemost 2022; 20:2646-2655. [PMID: 35971886 PMCID: PMC9826218 DOI: 10.1111/jth.15848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 01/11/2023]
Abstract
BACKGROUND The diagnosis of heparin-induced thrombocytopenia (HIT) requires functional assays to demonstrate that platelet factor 4 (PF4)-specific antibodies activate platelets, typically when therapeutic heparin (H) concentrations are tested ("classical" pattern). Some HIT samples also activate platelets without heparin ("atypical" pattern), but with unclear clinical significance. OBJECTIVES We aimed to assess whether platelet activation pattern and some characteristics of PF4-specific antibodies were associated with the severity of HIT. PATIENTS/METHODS Serotonin release assay (SRA) pattern of 81 HIT patients were analyzed and compared with their clinical and biological data, including levels of anti-PF4/H immunoglobulin G (IgG) and anti-PF4 IgG in 47 of them. RESULTS Higher anti-PF4/H IgG titers were measured in patients with an "atypical" SRA (optical density 2.52 vs. 1.94 in those with a "classical" pattern, p < .001). Patients of both groups had similar platelet count (PC) nadir and time to recovery, but those with an "atypical" SRA more frequently developed thrombotic events (69% vs. 34%, p = .037). Significant levels of anti-PF4 IgG were detected in both groups (38% and 61%, respectively). Whatever the SRA pattern, a lower PC nadir (35 vs. 53 G/L, p = .006) and a longer PC recovery time (6 vs. 3 days, p = .015) were evidenced in patients with anti-PF4 antibodies, compared with those with anti-PF4/H IgG only. CONCLUSIONS An atypical SRA pattern with elevated anti-PF4/H IgG titers seems associated with an increased risk of thrombosis in HIT. IgG antibodies to native PF4 may contribute to more severe and persistent thrombocytopenia, and their detection could be useful in clinical practice.
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Affiliation(s)
- Jérôme Rollin
- University of ToursToursFrance
- Department of HaemostasisRegional University Hospital Centre ToursToursFrance
| | | | - Yves Gruel
- University of ToursToursFrance
- Department of HaemostasisRegional University Hospital Centre ToursToursFrance
| | | | - Eve‐Anne Guéry
- Department of HaemostasisRegional University Hospital Centre ToursToursFrance
| | - Marc‐Antoine May
- Department of Cardiovascular SurgeryRegional University Hospital Centre ToursToursFrance
- Department of AnesthesiologyRegional University Hospital Centre ToursToursFrance
| | - Claire Pouplard
- University of ToursToursFrance
- Department of HaemostasisRegional University Hospital Centre ToursToursFrance
| | - Caroline Vayne
- University of ToursToursFrance
- Department of HaemostasisRegional University Hospital Centre ToursToursFrance
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7
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The interaction between anti-PF4 antibodies and anticoagulants in vaccine-induced thrombotic thrombocytopenia. Blood 2022; 139:3430-3438. [PMID: 35679071 PMCID: PMC8949646 DOI: 10.1182/blood.2021013839] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 03/18/2022] [Indexed: 02/08/2023] Open
Abstract
Life-threatening thrombotic events at unusual sites have been reported after vector-based vaccinations against severe acute respiratory syndrome coronavirus 2. This phenomenon is now termed vaccine-induced immune thrombotic thrombocytopenia (VITT). The pathophysiology of VITT is similar to that of heparin-induced thrombocytopenia (HIT) and is associated with platelet-activating antibodies (Abs) against platelet factor 4 (PF4). Therefore, current guidelines suggest nonheparin anticoagulants to treat VITT patients. In this study, we investigated the interactions of heparin, danaparoid, fondaparinux, and argatroban with VITT-Ab/PF4 complexes using an ex vivo model for thrombus formation as well as in vitro assays to analyze Ab binding and platelet activation. We found that immunoglobulin Gs (IgGs) from VITT patients induce increased adherent platelets/thrombus formation in comparison with IgGs from healthy controls. In this ex vivo flow-based model, the procoagulant activity of VITT IgGs was effectively inhibited with danaparoid and argatroban but also by heparin. Interestingly, heparin and danaparoid not only inhibited IgG binding to PF4 but were also able to effectively dissociate the preformed PF4/IgG complexes. Fondaparinux reduced the in vitro generation of procoagulant platelets and thrombus formation; however, it did not affect platelet aggregation. In contrast, argatroban showed no effect on procoagulant platelets and aggregation but significantly inhibited VITT-mediated thrombus formation. Taken together, our data indicate that negatively charged anticoagulants can disrupt VITT-Ab/PF4 interactions, which might serve as an approach to reduce Ab-mediated complications in VITT. Our results should be confirmed, however, in a clinical setting before a recommendation regarding the selection of anticoagulants in VITT patients could be made.
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8
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The clinical and laboratory diagnosis of vaccine-induced immune thrombotic thrombocytopenia. Blood Adv 2022; 6:4228-4235. [PMID: 35609563 PMCID: PMC9132380 DOI: 10.1182/bloodadvances.2022007766] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 05/16/2022] [Indexed: 11/20/2022] Open
Abstract
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but serious adverse syndrome occurring 5-30 days after adenoviral vector COVID-19 vaccination. Therefore, a practical evaluation of clinical assessments and laboratory testing for VITT is needed to prevent significant adverse outcomes as the global use of adenoviral vector vaccines continues. We received the clinical information and blood samples of 156 patient samples with a suspected diagnosis of VITT between April to July 2021 in Canada. The performance characteristics of various diagnostic laboratory tests were evaluated against the PF4-SRA including a commercial anti-PF4/heparin IgG/A/M enzyme immunoassay (EIA, PF4 Enhanced; Immucor), in-house IgG-specific anti-PF4 and anti-PF4/heparin-EIAs, the standard SRA, and the PF4/heparin-SRA. Of those, 43 (27.6%) had serologically confirmed VITT based on a positive PF4-SRA result and 113 (72.4%) were negative. The commercial anti-PF4/heparin EIA, the in-house anti-PF4-EIA, and anti-PF4/heparin-EIA were positive for all 43 VITT-confirmed samples (100% sensitivity) with a few false-positive results (mean specificity 95.6%). These immunoassays had specificities of 95.6% [95% confidence interval (CI) 90.0-98.6], 96.5% (95% CI 91.2-99.0), and 97.4% (95% CI 92.4-99.5), respectively. Functional tests, including the standard SRA and PF4/heparin-SRA, had high specificities (100%), but poor sensitivities for VITT [16.7% (95% CI 7.0-31.4); and 46.2% (95% CI 26.6-66.6), respectively]. These findings suggest EIA assays that can directly detect antibodies to PF4 or PF4/heparin have excellent performance characteristics and may be useful as a diagnostic test if the PF4-SRA is unavailable.
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9
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Warkentin TE, Greinacher A. Seminars in Hematology Laboratory testing for VITT antibodies. Semin Hematol 2022; 59:80-88. [DOI: 10.1053/j.seminhematol.2022.03.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 01/07/2023]
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10
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Pouplard C, Rollin J, Vayne C, Charuel N, Ahmadi Z, Alberio L, Azjenberg N, Althaus K, Bakchoul T, Chong B, Curtis BR, Faille D, Gomez FJ, Gresele P, Morel-Kopp MC, Mullier F, Nazy I, Smith JW, Greinacher A, Gruel Y. Multicentre evaluation of 5B9, a monoclonal anti-PF4/heparin IgG mimicking human HIT antibodies, as an internal quality control in HIT functional assays: Communication from the ISTH SSC Subcommittee on Platelet Immunology. J Thromb Haemost 2022; 20:252-259. [PMID: 34657390 DOI: 10.1111/jth.15560] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/13/2021] [Accepted: 10/14/2021] [Indexed: 12/29/2022]
Abstract
BACKGROUND Functional tests for the diagnosis of heparin-induced thrombocytopenia (HIT) exhibit variable performance. OBJECTIVES We evaluated in a multicenter study whether 5B9, a monoclonal anti-PF4/heparin IgG mimicking human HIT antibodies, could be used as an internal quality control. METHODS 5B9 was sent to 11 laboratories in seven countries, and six initial concentrations ranging from 10 to 400 μg/mL were tested by heparin-induced platelet activation assay (HIPA), serotonin release assay (SRA), platelet aggregation test (PAT), flow cytometry (FC), or heparin-induced multiple-electrode aggregometry (HIMEA). Each method was evaluated in three different laboratories using experimental procedures identical to those usually applied for the diagnosis of HIT by testing platelets from 10 different healthy donors. RESULTS The procedures used varied among the laboratories, particularly when platelet-rich plasma and whole blood were used. Nevertheless, positive results were obtained with at least 100 μg/ml of 5B9 for most donors tested by all centers (except one) performing HIPA, SRA, or HIMEA. FC and PAT results were more heterogeneous. FC results from one center that used washed platelets preincubated with PF4 were positive with all donors at 50 µg/ml 5B9, but at least 200 μg/ml of 5B9 were required to activate cells with most donors tested using PAT. CONCLUSION This study confirms that HIT functional tests are not well standardized and exhibit variable sensitivity for the detection of platelet-activating antibodies. However, 5B9 is a potentially useful tool to standardize functional tests, to select responding platelet donors, and consequently to improve the performance of these assays and comparability between laboratories.
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Affiliation(s)
- Claire Pouplard
- University of Tours, EA7501 GICC, CHRU de Tours, Department of Haemostasis, Tours, France
| | - Jérôme Rollin
- University of Tours, EA7501 GICC, CHRU de Tours, Department of Haemostasis, Tours, France
| | - Caroline Vayne
- University of Tours, EA7501 GICC, CHRU de Tours, Department of Haemostasis, Tours, France
| | - Noémie Charuel
- University of Tours, EA7501 GICC, CHRU de Tours, Department of Haemostasis, Tours, France
| | - Zohra Ahmadi
- Haematology Research Unit, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Lorenzo Alberio
- Service and Central Laboratory of Hematology, Lausanne University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
| | - Nadine Azjenberg
- University of Paris, INSERM U1148 LVTS, Department of Hematology, AP-HP, Bichat-Claude Bernard Hospital, Paris, France
| | - Karina Althaus
- Transfusion Medicine, Medical Faculty of Tubingen, University of Tubingen, Tubingen, Germany
| | - Tamam Bakchoul
- Transfusion Medicine, Medical Faculty of Tubingen, University of Tubingen, Tubingen, Germany
| | - Beng Chong
- Haematology Research Unit, St George and Sutherland Clinical School, University of New South Wales, Sydney, NSW, Australia
| | - Brian R Curtis
- Blood Research Institute, Versiti, Blood Center of Wisconsin, Milwaukee, Wisconsin, USA
| | - Dorothée Faille
- University of Paris, INSERM U1148 LVTS, Department of Hematology, AP-HP, Bichat-Claude Bernard Hospital, Paris, France
| | - Francisco-Javier Gomez
- Service and Central Laboratory of Hematology, Lausanne University Hospital (CHUV) and University of Lausanne, Lausanne, Switzerland
| | - Paolo Gresele
- Department of Medicine and Surgery, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia, Italy
| | - Marie-Christine Morel-Kopp
- Department of Haematology and Transfusion Medicine, Royal North Shore Hospital, and Northern Blood Research Centre, Kolling Institute, The University of Sydney, Sydney, NSW, Australia
| | - François Mullier
- Université catholique de Louvain, CHU UCL Namur, Namur Thrombosis and Hemostasis Center (NTHC), Hematology Laboratory, Namur Research for Life Sciences, Yvoir, Belgium
| | - Izhac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - James W Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
| | - Andreas Greinacher
- Institut fuer Immunologie und Transfusionsmedizin, Universitaetsmedizin Greifswald, Greifswald, Germany
| | - Yves Gruel
- University of Tours, EA7501 GICC, CHRU de Tours, Department of Haemostasis, Tours, France
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Abstract
Heparin-induced thrombocytopenia is a severe prothrombotic disease. Timely diagnosis and treatment are essential. Application of diagnostic algorithms based on validated clinical scoring tools and rapid, specific laboratory assays may improve outcomes.
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Gresele P, Momi S, Marcucci R, Ramundo F, De Stefano V, Tripodi A. Interactions of adenoviruses with platelets and coagulation and the vaccine-induced immune thrombotic thrombocytopenia syndrome. Haematologica 2021; 106:3034-3045. [PMID: 34407607 PMCID: PMC8634187 DOI: 10.3324/haematol.2021.279289] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 08/04/2021] [Indexed: 11/10/2022] Open
Abstract
The COVID-19 pandemic has had a heavy impact on global health and economy and vaccination remains the primary way of controlling the infection. During the ongoing vaccination campaign some unexpected thrombotic events have emerged in subjects who had recently received the AstraZeneca (Vaxzevria) vaccine or the Johnson and Johnson (Janssen) vaccine, two adenovirus vector-based vaccines. Epidemiological studies confirm that the observed/expected ratio of these unusual thromboses is abnormally increased, especially in women in fertile age. The characteristics of this complication, with venous thromboses at unusual sites, most frequently in the cerebral vein sinuses but also in splanchnic vessels, often with multiple associated thromboses, thrombocytopenia, and sometimes disseminated intravascular coagulation, are unique and the time course and tumultuous evolution are suggestive of an acute immunological reaction. Indeed, plateletactivating anti-PF4 antibodies have been detected in a large proportion of the affected patients. Several data suggest that adenoviruses may interact with platelets, the endothelium and the blood coagulation system. Here we review interactions between adenoviral vectors and the hemostatic system that are of possible relevance in vaccine-associated thrombotic thrombocytopenia syndrome. We systematically analyze the clinical data on the reported thrombotic complications of adenovirus-based therapeutics and discuss all the current hypotheses on the mechanisms triggering this novel syndrome. Although, considering current evidence, the benefit of vaccination clearly outweighs the potential risks, it is of paramount importance to fully unravel the mechanisms leading to vaccineassociated thrombotic thrombocytopenia syndrome and to identify prognostic factors through further research.
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Affiliation(s)
- Paolo Gresele
- Department of Medicine and Surgery, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia.
| | - Stefania Momi
- Department of Medicine and Surgery, Section of Internal and Cardiovascular Medicine, University of Perugia, Perugia
| | - Rossella Marcucci
- Department of Experimental and Clinical Medicine, University of Florence; Atherothrombotic Center, AOU Careggi, Florence
| | - Francesco Ramundo
- Section of Hematology, Department of Radiological and Hematological Sciences, Catholic University, Fondazione Policlinico A. Gemelli - IRCCS - Rome
| | - Valerio De Stefano
- Section of Hematology, Department of Radiological and Hematological Sciences, Catholic University, Fondazione Policlinico A. Gemelli - IRCCS - Rome
| | - Armando Tripodi
- Fondazione IRCCS Ca' Granda, Ospedale Maggiore Policlinico, Angelo Bianchi Bonomi Hemophilia and Thromboses Center, Milan
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13
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Arora K, Rodgers S, Alkhatib Y, Onwubiko IN, Padmanabhan A, Otrock ZK. P-selectin expression assay in a repeatedly serotonin-release assay-negative patient with heparin-induced thrombocytopenia. Blood Coagul Fibrinolysis 2021; 32:522-525. [PMID: 34261860 DOI: 10.1097/mbc.0000000000001062] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is an immune complication of heparin therapy caused by antibodies to complexes of platelet factor 4 (PF4) and heparin. Pathogenic antibodies to PF4/heparin bind and activate platelets to propagate a hypercoagulable state culminating in life-threatening thrombosis. The serotonin-release assay (SRA) is considered the gold-standard test to diagnose HIT. However, the sensitivity of the SRA was questioned with reported cases of clinical diagnosis of HIT and negative SRA. Herein, we present the utility of platelet factor 4-dependent P-selectin expression assay (PEA) in diagnosing HIT in a patient with thrombocytopenia and recurrent thrombosis who repeatedly tested negative with SRA.
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Affiliation(s)
| | | | - Yaser Alkhatib
- Division of Hematology and Oncology, Department of Internal Medicine, Henry Ford Hospital, Detroit, Michigan
| | | | - Anand Padmanabhan
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota
| | - Zaher K Otrock
- Department of Pathology and Laboratory Medicine
- Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan, USA
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14
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Anti-Platelet Drugs Block Platelet Activation by Vaccine-Induced Immune Thrombocytopenia and Thrombosis Patient Serum. Blood 2021; 138:2733-2740. [PMID: 34375398 PMCID: PMC8697531 DOI: 10.1182/blood.2021012277] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/05/2021] [Indexed: 11/20/2022] Open
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15
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Vayne C, Rollin J, Gruel Y, Pouplard C, Galinat H, Huet O, Mémier V, Geeraerts T, Marlu R, Pernod G, Mourey G, Fournel A, Cordonnier C, Susen S. PF4 Immunoassays in Vaccine-Induced Thrombotic Thrombocytopenia. N Engl J Med 2021; 385:376-378. [PMID: 34010527 PMCID: PMC8174029 DOI: 10.1056/nejmc2106383] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
| | | | - Yves Gruel
- Tours University Hospital, Tours, France
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16
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Nazy I, Sachs UJ, Arnold DM, McKenzie SE, Choi P, Althaus K, Ahlen MT, Sharma R, Grace RF, Bakchoul T. Recommendations for the clinical and laboratory diagnosis of VITT against COVID-19: Communication from the ISTH SSC Subcommittee on Platelet Immunology. J Thromb Haemost 2021; 19:1585-1588. [PMID: 34018298 PMCID: PMC8250233 DOI: 10.1111/jth.15341] [Citation(s) in RCA: 89] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/09/2021] [Accepted: 04/12/2021] [Indexed: 01/13/2023]
Abstract
Vaccine administration is under way worldwide to combat the current COVID-19 pandemic. The newly developed vaccines are highly effective with minimal adverse effects. Recently, the AstraZeneca ChadOx1 nCov-19 vaccine has raised public alarm with concerns regarding the rare, but serious, development of thrombotic events, now known as vaccine-induced immune thrombotic thrombocytopenia (VITT). These thrombotic events appear similar to heparin-induced thrombocytopenia, both clinically and pathologically. In this manuscript, the ISTH SSC Subcommittee on Platelet Immunology outlines guidelines on how to recognize, diagnose and manage patients with VITT.
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Affiliation(s)
- Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Ulrich J Sachs
- Department of Thrombosis and Haemostasis, Giessen University Hospital, Giessen, Germany
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Steven E McKenzie
- Cardeza Foundation for Hematological Research, Thomas Jefferson University, Philadelphia, PA, USA
| | - Phil Choi
- Haematology Department, The Canberra Hospital, Canberra, ACT, Australia
- John Curtin School of Medical Research, ANU, Canberra, ACT, Australia
| | - Karina Althaus
- Transfusion Medicine, Medical Faculty of Tuebingen, University of Tuebingen, Tuebingen, Germany
- Centre for Clinical Transfusion Medicine Tuebingen ZKT gGmbH, Tuebingen, Germany
| | - Maria Therese Ahlen
- Norwegian National Unit for Platelet Immunology, University Hospital of North Norway, Tromso, Norway
| | - Ruchika Sharma
- Versiti BloodCenter of Wisconsin Pediatric Hematology/Oncology, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Rachael F Grace
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, USA
| | - Tamam Bakchoul
- Institute for Clinical and Experimental Transfusion Medicine, Medical Faculty of Tuebingen, University Hospital of Tuebingen, Tuebingen, Germany
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17
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Rubino JG, Arnold DM, Warkentin TE, Smith JW, Kelton JG, Nazy I. A comparative study of platelet factor 4-enhanced platelet activation assays for the diagnosis of heparin-induced thrombocytopenia. J Thromb Haemost 2021; 19:1096-1102. [PMID: 33387395 DOI: 10.1111/jth.15233] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/06/2020] [Accepted: 12/28/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND Functional platelet activation assays, such as the serotonin release assay (SRA), are the gold standard for the diagnosis of heparin-induced thrombocytopenia (HIT). Recently, platelet activation assays using added platelet factor 4 (PF4) have been described and suggest improved sensitivity. Direct comparisons of these assays have not been performed. OBJECTIVE We compare the performance characteristics of three PF4-enhanced platelet activation assays, the PF4/heparin-SRA (PF4/hep-SRA), the PF4-SRA, and the P-selectin expression assay (PEA), at a single reference laboratory. METHODS Serum samples from two cohorts of patients were used. The referral cohort (n = 84) included samples that had previously undergone routine diagnostic testing for HIT and tested positive or negative using the SRA. The clinical cohort (n = 101) consisted of samples from patients with clinically confirmed HIT whose serum contained platelet-activating antibodies. We simultaneously tested all samples in PF4-enhanced SRA-based assays (PF4/hep-SRA, PF4-SRA) and the flow cytometry-based PEA. RESULTS In the referral cohort, the three PF4-enhanced assays identified all samples that were previously determined to be positive in the SRA. However, specificity of the PF4/hep-SRA was 96.6%, the PF4-SRA was 84.7%, and the PEA was 67.8%. In the clinical cohort of samples, all SRA-based assays displayed high performance characteristics (>92.1% sensitivity, >98.4% specificity). Sensitivity and specificity of the PEA was the lowest, 65.8% and 63.5%, respectively; but improved to 92.1% and 96.8% using preselected platelet donors. CONCLUSIONS All PF4-enhanced assays demonstrated good performance characteristics when platelet donors were preselected. Further comparisons across multiple laboratories should be conducted for consensus on optimal HIT diagnostic testing.
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Affiliation(s)
- Julian G Rubino
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - Donald M Arnold
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Theodore E Warkentin
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - James W Smith
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
| | - John G Kelton
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of Medicine, Hamilton, ON, Canada
- McMaster Centre for Transfusion Research, Hamilton, ON, Canada
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18
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Tardy-Poncet B, Montmartin A, Piot M, Alhenc-Gelas M, Nguyen P, Elalamy I, Greinacher A, Maistre ED, Lasne D, Horellou MH, Le Gal G, Lecompte T, Tardy B. Functional Flow Cytometric Assay for Reliable and Convenient Heparin-Induced Thrombocytopenia Diagnosis in Daily Practice. Biomedicines 2021; 9:biomedicines9040332. [PMID: 33806140 PMCID: PMC8064483 DOI: 10.3390/biomedicines9040332] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 03/19/2021] [Accepted: 03/20/2021] [Indexed: 12/19/2022] Open
Abstract
Reliable laboratory diagnosis of heparin-induced thrombocytopenia (HIT) remains a major clinical concern. Immunoassays are highly sensitive, while confirmatory functional tests (based on heparin-dependent platelet activation) lack standardization. We evaluated the diagnostic performance of a functional flow cytometric assay (FCA) based on the detection of heparin-dependent platelet activation with an anti-p-selectin. A total of 288 patients were included (131 HIT-positive and 157 HIT-negative) with a HIT diagnosis established by expert opinion adjudication (EOA) considering clinical data and local laboratory results. The FCA was centrally performed in a single laboratory on platelet-rich plasma, using a very simple four-color fluorometer. The results were standardized according to the Heparin Platelet Activation (HEPLA) index. The serotonin release assay (SRA) was performed in the four French reference laboratories. Based on the final HIT diagnosis established by EOA, the sensitivity and specificity of the FCA were 88 and 95%, respectively, values very similar to those of the SRA (88 and 97%, respectively). This study showed that the FCA, based on easily implementable technology, may be routinely used as a reliable confirmatory test for HIT diagnosis.
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Affiliation(s)
- Brigitte Tardy-Poncet
- Inserm U1059 Sainbiose, Université de Lyon, 42055 Saint-Etienne, France; (A.M.); (M.P.); (B.T.)
- Inserm CIC 1408, FCRIN-INNOVTE, Centre Hospitalier Universitaire de Saint-Etienne, 42000 Saint-Etienne, France
- Correspondence: ; Tel.: +33-(0)4-77-82-85-91
| | - Aurélie Montmartin
- Inserm U1059 Sainbiose, Université de Lyon, 42055 Saint-Etienne, France; (A.M.); (M.P.); (B.T.)
| | - Michele Piot
- Inserm U1059 Sainbiose, Université de Lyon, 42055 Saint-Etienne, France; (A.M.); (M.P.); (B.T.)
| | - Martine Alhenc-Gelas
- Service d’Hématologie biologique, Hôpital Européen Georges Pompidou, AP-HP, 75000 Paris, France;
| | - Philippe Nguyen
- Service d’Hématologie biologique, Pole de biologie, Hôpital Robert Debré, CHU de Reims, 51100 Reims, France;
| | - Ismail Elalamy
- Centre d’Hématologie et de Thrombose, Hôpital Tenon, Inserm U938, Université Sorbonne, 75000 Paris, France;
- Department of Obstetrics and Gynecology, I.M. Sechenov First Moscow State Medical University, 119435 Moscow, Russia
| | - Andreas Greinacher
- Institut d’Hématologie et de Médecine transfusionnelle, Université de Greifswald, 17489 Greifswald, Germany;
| | - Emmanuel De Maistre
- Service d’Hématologie Biologique, Hôpital Le Bocage, CHRU de Dijon, 21000 Dijon, France;
| | - Dominique Lasne
- Service d’Hématologie Biologique, Hôpital Necker-Enfants Malades, AP-HP, 75000 Paris, France;
| | | | - Grégoire Le Gal
- Département d’Hématologie, Departement de Medicine, Institut de Recherché de l’hôpital d’Ottawa, Université d’Ottawa, Ottawa, ON K1P 1J1, Canada;
| | - Thomas Lecompte
- Département de médecine, Hôpital Universitaire de Genève, Faculté de Médecine—Université de Genève, 57340 Genève, Switzerland;
| | - Bernard Tardy
- Inserm U1059 Sainbiose, Université de Lyon, 42055 Saint-Etienne, France; (A.M.); (M.P.); (B.T.)
- Inserm CIC 1408, FCRIN-INNOVTE, Centre Hospitalier Universitaire de Saint-Etienne, 42000 Saint-Etienne, France
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19
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Warkentin TE, Smythe MA, Ali MA, Aslam N, Sheppard JI, Smith JW, Moore JC, Arnold DM, Nazy I. Serotonin-release assay-positive but platelet factor 4-dependent enzyme-immunoassay negative: HIT or not HIT? Am J Hematol 2021; 96:320-329. [PMID: 33326124 DOI: 10.1002/ajh.26075] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 12/07/2020] [Accepted: 12/14/2020] [Indexed: 12/28/2022]
Abstract
IgG-specific and polyspecific PF4-dependent enzyme-immunoassays (EIAs) have exceptionally high sensitivity (≥99%) for diagnosis of heparin-induced thrombocytopenia (HIT), a drug reaction caused by platelet-activating antibodies detectable by serotonin-release assay (SRA). The IgG-specific EIAs are recommended for screening, as their high sensitivity is accompanied by relatively high specificity vis-à-vis polyspecific EIAs. We investigated the frequency of SRA-positive/EIA-negative (SRA+/EIA-) HIT, prompted by referral to our reference HIT laboratory of serial blood samples from a patient ("index case") with false-negative IgG-specific EIAs. Despite initial clinical suspicion for HIT, repeat negative IgG-specific EIAs prompted heparin resumption, which triggered recurrent thrombocytopenia and near-fatal cardiac arrest, indicating likely post-heparin HIT-associated anaphylactoid reaction. Further investigations revealed a strong-positive SRA, whether performed with heparin alone, PF4 alone, or PF4/heparin, with inhibition by Fc receptor-blocking monoclonal antibody (indicating IgG-mediated platelet activation); however, five different IgG-specific immunoassays yielded primarily negative (or weak-positive) results. To investigate the frequency of SRA+/EIA- HIT, we reviewed the laboratory and clinical features of patients with this serological profile during a 6-year period in which our reference laboratory investigated for HIT using both SRA and IgG-specific EIA. Although ~0.2% of 8546 patients had an SRA+/EIA- profile, further review of 15 such cases indicated clerical/laboratory misclassification or false-positive SRA in all, with no SRA+/EIA- HIT case identified. We conclude that while SRA+/EIA- HIT is possible-as shown by our index case-this clinical picture is exceptionally uncommon. Moreover, the requirement for a positive EIA is a useful quality control maneuver that reduces risk of reporting a false-positive SRA result.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Maureen A. Smythe
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
- Department of Pharmacy Practice Wayne State University Detroit Michigan USA
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Mona A. Ali
- Department of Pharmaceutical Services Beaumont Hospital Royal Oak Michigan USA
| | - Naveed Aslam
- Oakland University William Beaumont School of Medicine Rochester Michigan USA
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - James W. Smith
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Jane C. Moore
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - Donald M. Arnold
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Ishac Nazy
- Department of Medicine Michael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
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Samuelson Bannow B, Warad DM, Jones CG, Pechauer SM, Curtis BR, Bougie DW, Sharma R, Grill DE, Redman MW, Khalighi PR, Leger RR, Pruthi RK, Chen D, Sabath DE, Aster RH, Garcia DA, Padmanabhan A. A prospective, blinded study of a PF4-dependent assay for HIT diagnosis. Blood 2021; 137:1082-1089. [PMID: 32898858 PMCID: PMC7907721 DOI: 10.1182/blood.2020008195] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 08/23/2020] [Indexed: 12/22/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a life-threatening, prothrombotic, antibody-mediated disorder. To maximize the likelihood of recovery, early and accurate diagnosis is critical. Widely available HIT assays, such as the platelet factor 4 (PF4) heparin enzyme-linked immunosorbent assay (ELISA) lack specificity, and the gold-standard carbon 14-labeled serotonin release assay (SRA) is of limited value for early patient management because it is available only through reference laboratories. Recent studies have demonstrated that pathogenic HIT antibodies selectively activate PF4-treated platelets and that a technically simpler assay, the PF4-dependent P-selectin expression assay (PEA), may provide an option for rapid and conclusive results. Based upon predefined criteria that combined 4Ts scores and HIT ELISA results, 409 consecutive adults suspected of having HIT were classified as disease positive, negative, or indeterminate. Patients deemed HIT indeterminate were considered disease negative in the primary analysis and disease positive in a sensitivity analysis. The ability of PEA and SRA to identify patients judged to have HIT was compared using receiver operating characteristic curve statistics. Using these predefined criteria, the diagnostic accuracy of PEA was high (area under the curve [AUC], 0.94; 95% confidence interval [CI], 0.87-1.0) and similar to that of SRA (AUC, 0.91; 95% CI, 0.82-1.0). In sensitivity analysis, the AUCs of PEA and SRA were also similar at 0.88 (95% CI, 0.78-0.98) and 0.86 (95% CI, 0.77-0.96), respectively. The PEA, a technically simple nonradioactive assay that uses ∼20-fold fewer platelets compared with the SRA, had high accuracy for diagnosing HIT. Widespread use of the PEA may facilitate timely and more effective management of patients with suspected HIT.
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Affiliation(s)
| | - Deepti M Warad
- Department of Pediatric and Adolescent Medicine and
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | | | | | - Brian R Curtis
- Platelet and Neutrophil Immunology Laboratory, Versiti Wisconsin, Milwaukee, WI
| | | | - Ruchika Sharma
- Platelet and Neutrophil Immunology Laboratory, Versiti Wisconsin, Milwaukee, WI
| | - Diane E Grill
- Department of Health Sciences Research, Mayo Clinic, Rochester, MN
| | | | - Parisa R Khalighi
- Department of Obstetrics and Gynecology, University of Colorado, Denver, CO
| | - Rachel R Leger
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Rajiv K Pruthi
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
- Department of Medicine, Mayo Clinic, Rochester, MN; and
| | - Dong Chen
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
| | - Daniel E Sabath
- Department of Laboratory Medicine and
- Department of Medicine, University of Washington, Seattle, WA
| | | | - David A Garcia
- Department of Medicine, University of Washington, Seattle, WA
| | - Anand Padmanabhan
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN
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21
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Heparin-Induced Thrombocytopenia: A Review of New Concepts in Pathogenesis, Diagnosis, and Management. J Clin Med 2021; 10:jcm10040683. [PMID: 33578859 PMCID: PMC7916628 DOI: 10.3390/jcm10040683] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/29/2021] [Accepted: 01/30/2021] [Indexed: 12/17/2022] Open
Abstract
Knowledge on heparin-induced thrombocytopenia keeps increasing. Recent progress on diagnosis and management as well as several discoveries concerning its pathogenesis have been made. However, many aspects of heparin-induced thrombocytopenia remain partly unknown, and exact application of these new insights still need to be addressed. This article reviews the main new concepts in pathogenesis, diagnosis, and management of heparin-induced thrombocytopenia.
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22
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Marashi-Sabouni Z, Vayne C, Ibrahim-Kosta M, Guidon C, Loundou A, Guery EA, Morange PE, Camoin-Jau L. Clinical validation of immunoassay HemosIL® AcuStar HIT-IgG (PF4-H) in the diagnosis of Heparin-induced thrombocytopenia. J Thromb Thrombolysis 2021; 52:601-609. [PMID: 33386560 DOI: 10.1007/s11239-020-02349-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/17/2020] [Indexed: 11/25/2022]
Abstract
Heparin induced thrombocytopenia (HIT) is a life and limb-threatening complication of heparin exposure. The misdiagnosis of this disease can have major consequences on the patients. The objective of this study was to evaluate a diagnostic strategy that combines the 4Ts score with the result of HemosIL® AcuStar HIT-IgG (PF4-H) to confirm the diagnosis of HIT. Citrated plasmas from 1300 patients with suspicion of HIT were analyzed with a fully automated quantitative chemiluminescent immunoassay (HemosIL® AcuStar HIT-IgG (PF4/H)). If the IgG anti-PF4/H antibodies were positive (cut-off, 1 U/mL), HIT diagnosis was confirmed using functional tests. In total, 1300 samples of consecutive patients were enrolled, 94 (7.2%) of which gave positive results in HemosIL® AcuStar-IgG. HIT was diagnosed in 65 out of these patients, corresponding to a prevalence of 5%. Using ROC curve analysis, patients were divided into three groups according to their titer of antibodies. Higher values of the IgG (PF4-H) were associated with increased probability of HIT, and the diagnostic specificity was greatly increased using the combination of a 4Ts score > 3 and a positive titer ≥ 3.25 U/mL. Importantly, the diagnostic specificity is 100% when the titer is > 12.40 U/mL. We demonstrated that higher values of Anti PF4/H Antibodies were associated with a high probability of having HIT. A titer of HemosIL® IgG (PF4-H) > 12.40 U/mL has a specificity of 100% which should no require a functional test to confirm the diagnosis of HIT.
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Affiliation(s)
- Zeina Marashi-Sabouni
- Laboratoire d'Hématologie, La Timone Hospital, APHM, Boulevard Jean- Moulin, 13005, Marseille, France
| | - Caroline Vayne
- Service d'Hématologie Hémostase, Hôpital Trousseau, CHU de Tours, 37044, Tours, France
- EA7501 GICC, Université de Tours, Tours, France
| | - Manal Ibrahim-Kosta
- Laboratoire d'Hématologie, La Timone Hospital, APHM, Boulevard Jean- Moulin, 13005, Marseille, France
- Aix Marseille Univ, INSERM, INRAE, C2VN, Marseille, France
| | - Catherine Guidon
- Department of Anaesthesiology and Critical Care Medicine, University Hospital Timone, Marseille, France
| | - Anderson Loundou
- Biostatistic and Public Health Department, La Timone Hospital, Marseille, France
| | - Eve Anne Guery
- Service d'Hématologie Hémostase, Hôpital Trousseau, CHU de Tours, 37044, Tours, France
| | - Pierre-Emmanuel Morange
- Laboratoire d'Hématologie, La Timone Hospital, APHM, Boulevard Jean- Moulin, 13005, Marseille, France
- Aix Marseille Univ, INSERM, INRAE, C2VN, Marseille, France
| | - Laurence Camoin-Jau
- Laboratoire d'Hématologie, La Timone Hospital, APHM, Boulevard Jean- Moulin, 13005, Marseille, France.
- Aix Marseille Univ, IRD, APHM, MEPHI, IHU Méditerranée Infection, Marseille, France.
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23
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Jousselme E, Guéry EA, Nougier C, Sobas F, Rollin J, Gruel Y, Vayne C, Pouplard C. Prospective evaluation of two specific IgG immunoassays (HemosIL ® AcuStar HIT-IgG and HAT45G ® ) for the diagnosis of heparin-induced thrombocytopenia: A Bayesian approach. Int J Lab Hematol 2020; 43:468-476. [PMID: 33244896 DOI: 10.1111/ijlh.13404] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Revised: 09/30/2020] [Accepted: 10/21/2020] [Indexed: 12/11/2022]
Abstract
INTRODUCTION The accurate diagnosis of heparin-induced thrombocytopenia (HIT) is essential to ensure adequate treatment and prevent complications. First step diagnosis test are immunoassays including enzyme-linked immunosorbent assays (ELISAs) and rapid immunoassays. METHODS Using a Bayesian approach, we prospectively evaluated the performance of the IgG PF4/polyvinylsulfonate ELISA and a chemiluminescent immunoassay (CLIA), which are specific for IgG and use the same antigenic target to detect HIT antibodies. RESULTS One hundred and eighty-four 184 consecutive patients with an intermediate (n = 159) or high (n = 25) clinical pretest probability of HIT based on the 4Ts score or platelet pattern were included. Both immunoassays (IAs) were performed on all 184 samples, and definite HIT was confirmed with a positive serotonin release assay in 29 patients (12.7%). The sensitivity (Ss) and negative predictive value (NPV) of ELISA were excellent (100%) allowing HIT to be excluded with good confidence when the test was negative. In addition, the Ss and NPV of the CLIA equalled 93.1% and 98.6%, respectively, as it was negative in two definite HIT. When the CLIA was negative, the post-test probability of HIT was 0.7% in case of intermediate risk. Although there was excellent agreement between CLIA and ELISA results, the quantitative values provided by the two IAs were not correlated. CONCLUSION AcuStar HIT® detects more than 90% of HIT, as do all rapid IAs, and appears to be a good tool for excluding HIT when the pretest probability is intermediate. A chemiluminescent signal higher than 10 IU/mL is highly predictive of definite HIT with a PPV of 100%.
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Affiliation(s)
- Emilie Jousselme
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Eve-Anne Guéry
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France
| | - Christophe Nougier
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Frédéric Sobas
- Department of Haematology-Haemostasis, Civil Hospices of Lyon, Bron, France
| | - Jérôme Rollin
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Yves Gruel
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Caroline Vayne
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
| | - Claire Pouplard
- Department of Haematology-Haemostasis, Regional University Hospital of Tours, Tours, France.,EA 7501 GICC, University of Tours, Tours, France
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Abstract
A striking feature of COVID-19 is the high frequency of thrombosis, particularly in patients who require admission to intensive care unit because of respiratory complications (pneumonia/adult respiratory distress syndrome). The spectrum of thrombotic events is wide, including in situ pulmonary thrombosis, deep-vein thrombosis and associated pulmonary embolism, as well as arterial thrombotic events (stroke, myocardial infarction, limb artery thrombosis). Unusual thrombotic events have also been reported, e.g., cerebral venous sinus thrombosis, mesenteric artery and vein thrombosis. Several hematology abnormalities have been observed in COVID-19 patients, including lymphopenia, neutrophilia, thrombocytopenia (usually mild), thrombocytosis, elevated prothrombin time and partial thromboplastin times (the latter abnormality often indicating lupus anticoagulant phenomenon), hyperfibrinogenemia, elevated von Willebrand factor levels, and elevated fibrin d-dimer. Many of these abnormal hematologic parameters—even as early as the time of initial hospital admission—indicate adverse prognosis, including greater frequency of progression to severe respiratory illness and death. Progression to overt disseminated intravascular coagulation in fatal COVID-19 has been reported in some studies, but not observed in others. We compare and contrast COVID-19 hypercoagulability, and associated increased risk of venous and arterial thrombosis, from the perspective of heparin-induced thrombocytopenia (HIT), including the dilemma of providing thromboprophylaxis and treatment recommendations when available data are limited to observational studies. The frequent use of heparin—both low-molecular-weight and unfractionated—in preventing and treating COVID-19 thrombosis, means that vigilance for HIT occurrence is required in this patient population. HIT and COVID-19 are associated with a high risk of thrombosis (venous > arterial). HIT and COVID-19 both feature coagulation and “pancellular” activation. Therapeutic anticoagulation is indicated for HIT, but dosing unknown for COVID-19.
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25
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Riker RR, May TL, Fraser GL, Gagnon DJ, Bandara M, Zemrak W, Seder DB. Response to The challenges of diagnosing heparin-induced thrombocytopenia in patients with COVID-19. Res Pract Thromb Haemost 2020; 4:1068-1069. [PMID: 32838110 PMCID: PMC7361545 DOI: 10.1002/rth2.12417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2020] [Accepted: 07/01/2020] [Indexed: 11/30/2022] Open
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26
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Koster A, Nazy I, Birschmann IE, Smith JW, Sheppard JI, Warkentin TE. High-dose IVIG plus cangrelor platelet "anesthesia" during urgent heparin-CPB in a patient with recent SRA-negative HIT-thrombosis with persisting platelet-activating antibodies. Res Pract Thromb Haemost 2020; 4:1060-1064. [PMID: 32864557 PMCID: PMC7443421 DOI: 10.1002/rth2.12348] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 03/31/2020] [Indexed: 11/24/2022] Open
Abstract
In a high-risk patient with subacute heparin-induced thrombocytopenia (HIT) type A (platelet count recovery following acute HIT but with persisting platelet-activating antibodies), in whom urgent cardiac surgery was required, a key clinical question arose: could intraoperative heparin be given safely with "platelet anesthesia" provided with high-dose intravenous immunoglobulin (IVIG) plus cangrelor (ultra-short-acting antiplatelet agent)? This approach proved successful, without unexpected postoperative thrombocytopenia or thromboembolism. In vitro studies confirmed that both IVIG and cangrelor contributed to perioperative inhibition of HIT antibody-induced platelet activation. Interestingly, despite the patient testing strongly positive in 4 HIT immunoassays (latex immunoturbidimetric assay and 3 enzyme-immunoassays), the serotonin-release assay (SRA) was consistently negative. Nevertheless, platelet-activating HIT antibodies were detectable using modified (platelet factor 4-enhanced) SRA. Our protocol of heparin rechallenge following IVIG/cangrelor provides both intraoperative and early postoperative inhibition of HIT antibody-induced platelet activation and is applicable to patients with circulating functional HIT antibodies requiring urgent heart surgery, including those with "SRA-negative HIT."
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Affiliation(s)
- Andreas Koster
- Institute of Anesthesiology and Pain Therapy, Heart and Diabetes Center NRWRuhr‐University BochumBad OeynhausenGermany
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Ingvild E. Birschmann
- Institute of Laboratory and Transfusion Medicine, Heart and Diabetes Center NRWRuhr‐University BochumBad OeynhausenGermany
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Theodore E. Warkentin
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
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Riker RR, May TL, Fraser GL, Gagnon DJ, Bandara M, Zemrak WR, Seder DB. Heparin-induced thrombocytopenia with thrombosis in COVID-19 adult respiratory distress syndrome. Res Pract Thromb Haemost 2020; 4:936-941. [PMID: 32685905 PMCID: PMC7276726 DOI: 10.1002/rth2.12390] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/08/2020] [Accepted: 05/13/2020] [Indexed: 01/08/2023] Open
Abstract
Early reports of coronavirus disease 2019 (COVID-19) clinical features describe a hypercoagulable state, and recent guidelines recommend prophylactic anticoagulation for patients with COVID-19 with low-molecular-weight heparin, but this would be contraindicated in the presence of heparin-induced thrombocytopenia (HIT). We address the key clinical question whether HIT is also present during COVID-19. We report 3 cases of thrombocytopenia with antiplatelet factor 4 antibodies among 16 intubated patients with COVID-19 with adult respiratory distress syndrome, a higher-than-expected incidence of 19%. Each patient had evidence of thrombosis (pulmonary embolism, upper extremity venous thromboses, and skin necrosis, respectively). The serotonin release assay confirmed HIT in 1 case, and 2 cases were negative. We believe this is the first reported case of HIT during the COVID-19 pandemic. Recognition that the thrombocytopenia represented HIT in the confirmed case was delayed. We recommend clinicians monitor platelet counts closely during heparin therapy, with a low threshold to evaluate for HIT.
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Warkentin TE, Sheppard JI, Smith JW, Li N, Moore JC, Arnold DM, Nazy I. Combination of two complementary automated rapid assays for diagnosis of heparin-induced thrombocytopenia (HIT). J Thromb Haemost 2020; 18:1435-1446. [PMID: 32167669 PMCID: PMC7317897 DOI: 10.1111/jth.14794] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 03/10/2020] [Indexed: 12/16/2022]
Abstract
BACKGROUND HIT diagnosis typically uses complementary diagnostic assays (eg, a PF4-dependent enzyme-immunoassay [EIA] and a platelet activation assay such as the serotonin-release assay [SRA]). OBJECTIVES To determine whether the combination of two automated assays-a latex immunoturbidimetric assay (LIA) that evaluates competitive inhibition of a HIT-like monoclonal antibody and a chemiluminescence immunoassay (CLIA) for detecting anti-PF4/heparin IgG-optimizes diagnostic sensitivity while also yielding good specificity, particularly at high assay reactivities. PATIENTS/METHODS We determined operating characteristics using combined LIA/CLIA results from a HIT observational trial (n = 430; derivation cohort) and 147 consecutive patients with HIT (n = 147; supplementary derivation cohort). We also evaluated 678 consecutive samples referred for HIT testing (replication cohort). LIA/CLIA reactivities were scored individually as "negative" (<1.00 U/mL, 0 points), "weak" (1.00-4.99 U/mL, 1 point), "moderate" (5.00-15.99 U/mL, 2 points) and "strong" (≥16.00 U/mL, 3 points), thus contributing up to 6 points (maximum) when LIA/CLIA results were combined. We also examined whether higher LIA/CLIA scores predicted presence of platelet-activating antibodies by conventional and modified (PF4- or PF4/heparin-enhanced) SRA. RESULTS Combined LIA/CLIA testing yielded high diagnostic sensitivity (~99%) similar to EIA. Interpretation of LIA/CLIA results using the 6-point scale indicated progressively greater likelihood for the presence of platelet-activating antibodies with increasing scores (semi-quantitative reactivity). A LIA/CLIA score ≥ 4 points predicted the presence of platelet-activating antibodies by SRA or PF4-enhanced SRA with high probability (~98%). CONCLUSION Combined LIA/CLIA testing optimizes diagnostic sensitivity, with progressively greater probability of detecting platelet-activating antibodies with higher assay reactivity that reaches 98% when both automated assays yield moderate or strong results.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- Hamilton Regional Laboratory Medicine ProgramHamilton Health SciencesHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Na Li
- McMaster Centre for Transfusion ResearchHamiltonONCanada
- Department of Computing and SoftwareMcMaster UniversityHamiltonONCanada
| | - Jane C. Moore
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
| | - Donald M. Arnold
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of MedicineMcMaster UniversityHamiltonONCanada
- McMaster Centre for Transfusion ResearchHamiltonONCanada
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Tardy B, Lecompte T, Mullier F, Vayne C, Pouplard C. Detection of Platelet-Activating Antibodies Associated with Heparin-Induced Thrombocytopenia. J Clin Med 2020; 9:jcm9041226. [PMID: 32344682 PMCID: PMC7230370 DOI: 10.3390/jcm9041226] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 04/17/2020] [Accepted: 04/19/2020] [Indexed: 12/13/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic immune drug reaction caused by platelet-activating antibodies that in most instances recognize platelet factor 4 (PF4)/polyanion complexes. Platelet activation assays (i.e., functional assays) are more specific than immunoassays, since they are able to discern clinically relevant heparin-induced antibodies. All functional assays used for HIT diagnosis share the same principle, as they assess the ability of serum/plasma from suspected HIT patients to activate fresh platelets from healthy donors in the presence of several concentrations of heparin. Depending on the assay, donors’ platelets are stimulated either in whole blood (WB), platelet-rich plasma (PRP), or in a buffer medium (washed platelets, WP). In addition, the activation endpoint studied varies from one assay to another: platelet aggregation, membrane expression of markers of platelet activation, release of platelet granules. Tests with WP are more sensitive and serotonin release assay (SRA) is considered to be the current gold standard, but functional assays suffer from certain limitations regarding their sensitivity, specificity, complexity, and/or accessibility. However, the strict adherence to adequate preanalytical conditions, the use of selected platelet donors and the inclusion of positive and negative controls in each run are key points that ensure their performances.
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Affiliation(s)
- Brigitte Tardy
- Inserm U1059 Sainbiose, University of Lyon St Etienne, CIC 1408, FCRIN-INNOVTE, Hémostase Clinique CHU, 42055 Saint Etienne, France
| | - Thomas Lecompte
- Department of Medicine, Geneva University Hospitals, and Geneva Platelet Group (GpG), Faculty of Medicine, University of Geneva, CH-1211 Genève 14
| | - François Mullier
- CHU UCL Namur, Namur Thrombosis and Hemostasis center (NTHC), Hematology Laboratory, Université Catholique de Louvain, 5530 Yvoir, Belgium
| | - Caroline Vayne
- Department of Hemostasis, University Hospital of Tours, 37044 Tours, France
- University of Tours, EA 7501 GICC, 37000 Tours, France
| | - Claire Pouplard
- Department of Hemostasis, University Hospital of Tours, 37044 Tours, France
- University of Tours, EA 7501 GICC, 37000 Tours, France
- Correspondence:
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31
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Vayne C, Guéry EA, Charuel N, Besombes J, Lambert WC, Rollin J, Gruel Y, Pouplard C. Evaluation of functional assays for the diagnosis of heparin induced thrombocytopenia using 5B9, a monoclonal IgG that mimics human antibodies. J Thromb Haemost 2020; 18:968-975. [PMID: 31997532 DOI: 10.1111/jth.14749] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 01/24/2020] [Accepted: 01/27/2020] [Indexed: 12/13/2022]
Abstract
BACKGROUND Serotonin release assay (SRA) is considered as the "gold standard" for detecting pathogenic heparin-induced thrombocytopenia (HIT) antibodies. However, this method is time consuming, expensive, and uses radioelements. Heparin-induced multiple electrode aggregometry (HIMEA), light transmission aggregometry (LTA) with platelet rich plasma (PRP) or washed platelets (WP), adenosine triphosphate (ATP) release, and flow cytometry (FC) are available alternatives. OBJECTIVES To evaluate the performance of these assays, comparatively with SRA, for detecting HIT antibodies, using 5B9, a monoclonal IgG fully mimicking human HIT antibodies. PATIENTS/METHODS Heparin-dependent platelet activation induced by 5B9 (50/20/10 µg/mL) was evaluated by all assays performed on the same day using platelets from 20 healthy donors. The three methods exhibiting the highest sensitivity to 5B9 were then assessed by testing samples from patients with either likely (n = 10), or indeterminate/unlikely HIT (n = 10). RESULTS All methods exhibited good sensitivity for detecting 5B9 50 µg/mL, but only SRA and HIMEA were positive with 100% of donors using 5B9 20 µg/mL, followed by FC (83%). SRA detected 5B9 10 μg/mL with 90% of donors, while HIMEA and FC were positive in 45% and 44% of cases, respectively. Whereas SRA was positive with 9/10 samples from likely HIT, HIMEA and FC were positive with 6 and 7 of them, respectively. Neither SRA nor HIMEA was positive with indeterminate/unlikely HIT samples, while FC was positive or doubtful in three cases. CONCLUSIONS Serotonin release assay likely remains the most sensitive and specific assay for detecting platelet activating HIT antibodies, but HIMEA or FC are potential alternatives, despite being less performant.
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Affiliation(s)
- Caroline Vayne
- Department of Haemostasis, University Hospital of Tours, Tours, France
- EA 7501 GICC, University of Tours, Tours, France
| | - Eve-Anne Guéry
- Department of Haemostasis, University Hospital of Tours, Tours, France
| | | | - Joevin Besombes
- Department of Haemostasis, University Hospital of Tours, Tours, France
| | - Wayne C Lambert
- Department of Haemostasis, University Hospital of Tours, Tours, France
| | - Jérôme Rollin
- Department of Haemostasis, University Hospital of Tours, Tours, France
- EA 7501 GICC, University of Tours, Tours, France
| | - Yves Gruel
- Department of Haemostasis, University Hospital of Tours, Tours, France
- EA 7501 GICC, University of Tours, Tours, France
| | - Claire Pouplard
- Department of Haemostasis, University Hospital of Tours, Tours, France
- EA 7501 GICC, University of Tours, Tours, France
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Warkentin TE, Nazy I, Sheppard JI, Smith JW, Kelton JG, Arnold DM. Serotonin-release assay-negative heparin-induced thrombocytopenia. Am J Hematol 2020; 95:38-47. [PMID: 31621093 DOI: 10.1002/ajh.25660] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 10/09/2019] [Accepted: 10/13/2019] [Indexed: 12/22/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic drug reaction caused by platelet-activating anti-platelet factor 4 (PF4)/heparin antibodies. Pathogenic HIT antibodies can be detected by the serotonin-release assay (SRA), a platelet activation test. We have regarded the SRA performed in our medical community ("McMaster" SRA) as having high sensitivity and specificity. Recently, the concept of "SRA-negative HIT" has been proposed for enzyme-immunoassay (EIA)-positive/SRA-negative patients with a HIT-compatible clinical picture, who test positive in a PF4-enhanced platelet activation assay. After identifying an index case of SRA-negative HIT, we estimated the frequency of this condition by performing the "PF4-SRA" (modified SRA using high concentrations of added PF4 rather than heparin) in EIA-positive patients from a cohort study evaluating clinical and laboratory diagnosis of HIT. We defined SRA-negative HIT as patients meeting three criteria: clinical picture compatible with HIT (4Ts ≥ 4 points); EIA-positive (≥1.00 units); and PF4-SRA-positive. Among 430 patients, 35 were EIA-positive/SRA-positive and 27 were EIA-positive/SRA-negative. Among these 27 SRA-negative patients, three were found to have subthreshold levels of platelet-activating antibodies by PF4-SRA, of whom one met clinical criteria for SRA-negative HIT. Thus, based on identifying one patient with SRA-negative HIT within a cohort study that found 35 SRA-positive HIT patients, we estimate the sensitivity of the McMaster SRA for diagnosis of HIT to be 35/36 (97.2%; 95% CI, 85.8-99.9%). Although the McMaster SRA is highly sensitive for HIT, occasional SRA-negative but EIA-positive patients strongly suspected of having HIT can have this diagnosis supported by a PF4-enhanced activation assay such as the PF4-SRA.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Ishac Nazy
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - James W. Smith
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
| | - John G. Kelton
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
| | - Donald M. Arnold
- Department of MedicineMichael G. DeGroote School of Medicine Hamilton Ontario Canada
- McMaster Centre for Transfusion Research Hamilton Ontario Canada
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Chawla D, Saad E, Khairi T, Padmanabhan A. Severe persistent heparin-induced thrombocytopenia in a renal transplant patient. Thromb Res 2019; 183:106-107. [PMID: 31677588 DOI: 10.1016/j.thromres.2019.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 09/27/2019] [Accepted: 10/16/2019] [Indexed: 01/29/2023]
Affiliation(s)
- Divya Chawla
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Ehab Saad
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Talal Khairi
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Anand Padmanabhan
- Blood Research Institute, Versiti Wisconsin, Milwaukee, WI, USA; Department of Pathology, Medical College of Wisconsin, Milwaukee, WI, USA.
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Warkentin TE, Sheppard JI, Smith JW, Arnold DM, Nazy I. Timeline of heparin-induced thrombocytopenia seroconversion in serial plasma samples tested using an automated latex immunoturbidimetric assay. Int J Lab Hematol 2019; 41:493-502. [PMID: 31050876 PMCID: PMC6850468 DOI: 10.1111/ijlh.13031] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 01/22/2023]
Abstract
INTRODUCTION HIT is caused by platelet-activating IgG that recognize multimolecular PF4/heparin complexes. HIT antibodies are generally detectable by PF4-dependent enzyme immunoassay (EIA) and by platelet serotonin-release assay (SRA) at the beginning of the HIT-related platelet count fall. We determined whether an automated immunoassay for HIT, the latex immunoturbidimetric assay (LIA), also detects antibodies early during the course of HIT. The LIA was also used to evaluate a patient with putative SRA-negative HIT. METHODS We evaluated the timing and magnitude of LIA reactivity in serial plasma samples obtained from 19 SRA-positive patients (17 with abnormal platelet count changes indicating HIT; two with subclinical seroconversion) and one putative SRA-negative HIT patient, all obtained from patients who participated in a clinical trial of heparin thromboprophylaxis. We determined LIA status at the onset of the HIT-related platelet count fall. RESULTS The LIA was positive in all 19 SRA-positive patients (median value, 7.3 U/mL [range, 1.2-35.5]; cutoff, 1.0 U/mL); for all 13 evaluable patients for whom an informative plasma sample was available at (or shortly before) the onset of the HIT-related platelet count fall, LIA reactivity was positive. Heterogeneity in seroconversion using the LIA was observed; some patients exhibited gradual increases in reactivity, whereas other patients showed rapid increase in reactivity over a few days. The single clinical trial patient who met clinical-pathological criteria for "SRA-negative HIT" tested LIA-positive. CONCLUSION The LIA detects HIT antibodies at the beginning of the HIT-associated platelet count fall. The LIA was also positive in a patient with SRA-negative HIT.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
- Hamilton Regional Laboratory Medicine ProgramHamilton Health SciencesHamiltonOntarioCanada
| | - Jo‐Ann I. Sheppard
- Department of Pathology and Molecular Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
| | - James W. Smith
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
| | - Donald M. Arnold
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
| | - Ishac Nazy
- Department of Medicine, Michael G. DeGroote School of MedicineMcMaster UniversityHamiltonOntarioCanada
- McMaster Centre for Transfusion ResearchHamiltonOntarioCanada
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Warkentin TE. Laboratory diagnosis of heparin-induced thrombocytopenia. Int J Lab Hematol 2019; 41 Suppl 1:15-25. [PMID: 31069988 DOI: 10.1111/ijlh.12993] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 01/25/2019] [Accepted: 02/01/2019] [Indexed: 12/18/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) is a clinical-pathological disorder; thus, laboratory testing for the pathogenic platelet-activating antiplatelet factor 4 (PF4)/heparin antibodies is central for diagnosis. The "iceberg" model summarizes the inter-relationship between platelet activation assays and PF4-dependent immunoassays, with platelet-activating antibodies comprising a subset of anti-PF4/heparin antibodies. The platelet serotonin-release assay (SRA), performed by reference laboratories, has high sensitivity and specificity for HIT (~95% each), and is especially suited for detecting highly pathogenic HIT sera containing both heparin-dependent and heparin-independent platelet-activating antibodies; this latter subgroup of antibodies explains "autoimmune HIT" disorders (delayed-onset, persisting, spontaneous, heparin "flush," fondaparinux-associated). Recently, SRA-negative HIT has become recognized, in which serum from some HIT patients contains subthreshold levels of platelet-activating antibodies (by SRA) that become detectable using a PF4-enhanced platelet activation assay. Unusual immunologic features of HIT include early antibody detectability (at onset of platelet count fall) and antibody transience (seroreversion). Widely available PF4-dependent enzyme immunoassays (EIAs) have high sensitivity but poor specificity for HIT, although specificity is enhanced with IgG-specific EIAs and strong positive results; unfortunately, EIA results are usually not available in real time. Automated rapid immunoassays, such as the chemiluminescence immunoassay (CLIA) and latex immunoturbidimetric assay (LIA), facilitate real-time laboratory diagnosis. Recently available likelihood ratio (LR) data for positive (LR+) and negative (LR-) test results allow clinicians to adjust their pretest probabilities for HIT, using Bayesian analysis, into real-time posttest probabilities that are dramatically increased (test positive) or decreased (test negative). Moreover, (semi-)quantitative CLIA- and LIA-positive results (weak, moderate, strong positive) can further refine the posttest probability of HIT.
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Affiliation(s)
- Theodore E Warkentin
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Department of Pathology and Molecular Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada.,Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences, Hamilton General Hospital, Hamilton, Ontario, Canada.,McMaster Centre for Transfusion Research, Hamilton, Ontario, Canada
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Evaluation of a flow cytometer-based functional assay using platelet-rich plasma in the diagnosis of heparin-induced thrombocytopenia. Thromb Res 2019; 180:55-61. [PMID: 31220752 DOI: 10.1016/j.thromres.2019.05.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/07/2019] [Accepted: 05/20/2019] [Indexed: 01/25/2023]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating antibodies that recognize platelet factor 4/heparin (PF4/hep)-complexes. The in vitro demonstration of PF4/hep antibodies using functional assays is essential for an optimal management of patients suspected to have HIT. However, conventional functional assays are technically challenging and limited to specialized laboratories. In contrast, flow cytometers are commonly used in routine laboratories. The aim of this study is to investigate the performance characteristics of a commercially available, flow cytometer based assay in the diagnosis of HIT. STUDY DESIGN Sera of consecutive patients with suspected HIT were investigated using the Emo-test HIT Confirm® assay and compared to the standard method consisting of an IgG-specific enzyme immunoassay (EIA) for anti-PF4/hep antibodies and the heparin induced platelet aggregation (HIPA) test. RESULTS 390 sera were included in the study, 164 sera tested IgG EIA-positive, of which 33 also tested HIPA-positive. No HIPA-positive samples were EIA-negative. In the Emo-test HIT Confirm® assay, 112 sera revealed positive results (%Hepla > 13); however, 51 (45.5%) were EIA-negative. Of the 33 HIPA-positive/EIA-positive HIT sera, 23 tested positive in the Emo-test HIT Confirm® assay, 2 gave ambiguous results, and 8 sera yielded false-negative results. Accordingly, the HIT Confirm® assay showed a sensitivity of 69.7% with a slightly better specificity of 75.4% compared to the EIA (sensitivity 100%, specificity 63.3%). An increase in diagnostic specificity for HIT to 85% was found when positive results were obtained in both the Emo-test HIT Confirm® assay and EIA. CONCLUSION The Emo-Test HIT Confirm® assay may improve the specificity of laboratory investigations of HIT. However, the assay can only be recommended in combination with an immunoassay due to the high rate of false negativity. Our observation indicates a need to establish external quality assessment for functional assays to avoid such clinically relevant pitfalls.
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Heparin-Induced Thrombocytopenia. Platelets 2019. [DOI: 10.1016/b978-0-12-813456-6.00041-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Pandya KA, Johnson EG, Davis GA, Padmanabhan A. Serotonin release assay (SRA)-negative HIT, a newly recognized entity: Implications for diagnosis and management. Thromb Res 2018; 172:169-171. [DOI: 10.1016/j.thromres.2018.10.022] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 10/17/2018] [Accepted: 10/24/2018] [Indexed: 01/09/2023]
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Bakchoul T, Marini I. Drug-associated thrombocytopenia. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2018; 2018:576-583. [PMID: 30504360 PMCID: PMC6246020 DOI: 10.1182/asheducation-2018.1.576] [Citation(s) in RCA: 59] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Many drugs have been implicated in drug-induced immune thrombocytopenia (DITP). Patients with DITP develop a drop in platelet count 5 to 10 days after drug administration with an increased risk of hemorrhage. The diagnosis of DITP is often challenging, because most hospitalized patients are taking multiple medications and have comorbidities that can also cause thrombocytopenia. Specialized laboratory diagnostic tests have been developed and are helpful to confirm the diagnosis. Treatment of DITP involves discontinuation of the offending drug. The platelet count usually starts to recover after 4 or 5 half-lives of the responsible drug or drug metabolite. High doses of intravenous immunoglobulin can be given to patients with severe thrombocytopenia and bleeding. Although in most cases, DITP is associated with bleeding, life-threatening thromboembolic complications are common in patients with heparin-induced thrombocytopenia (HIT). Binding of antiplatelet factor 4/heparin antibodies to Fc receptors on platelets and monocytes causes intravascular cellular activation, leading to an intensely prothrombotic state in HIT. The clinical symptoms include a decrease in platelet counts by >50% and/or new thromboembolic complications. Two approaches can help to confirm or rule out HIT: assessment of the clinical presentation using scoring systems and in vitro demonstration of antiplatelet factor 4/heparin antibodies. The cornerstone of HIT management is immediate discontinuation of heparin when the disease is suspected and anticoagulation using nonheparin anticoagulant. In this review, we will provide an update on the pathophysiology, diagnosis, and management of both DITP and HIT.
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Affiliation(s)
- Tamam Bakchoul
- Transfusion Medicine, Medical Faculty of Tubingen, University of Tubingen, Tubingen, Germany
| | - Irene Marini
- Transfusion Medicine, Medical Faculty of Tubingen, University of Tubingen, Tubingen, Germany
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Dai J, Madeeva D, Hayes V, Ahn HS, Tutwiler V, Arepally GM, Cines DB, Poncz M, Rauova L. Dynamic intercellular redistribution of HIT antigen modulates heparin-induced thrombocytopenia. Blood 2018; 132:727-734. [PMID: 29914979 PMCID: PMC6097133 DOI: 10.1182/blood-2018-02-830737] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 06/09/2018] [Indexed: 12/20/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder initiated by antibodies to platelet factor 4 (PF4)/heparin complexes. PF4 released from platelets binds to surface glycosaminoglycans on hematopoietic and vascular cells that are heterogenous in composition and differ in affinity for PF4. PF4 binds to monocytes with higher affinity than to platelets, and depletion of monocytes exacerbates thrombocytopenia in a murine HIT model. Here we show that the expression of PF4 on platelets and development of thrombocytopenia are modulated by the (re)distribution of PF4 among hematopoietic and endothelial cell surfaces. Binding of PF4 to platelets in whole blood in vitro varies inversely with the white cell count, likely because of the greater affinity of monocytes for PF4. In mice, monocyte depletion increased binding of PF4 to platelets by two- to three-fold. Induction of HIT in mice caused a transient >80-fold increase in binding of HIT antibody to monocytes vs 3.5-fold increase to platelets and rapid transient monocytopenia. Normalization of monocyte counts preceded the return in platelet counts. Exposure of blood to endothelial cells also depletes PF4 from platelet surfaces. These studies demonstrate a dynamic interchange of surface-bound PF4 among hematopoetic and vascular cells that may limit thrombocytopenia at the expense of promoting prothrombotic processes in HIT.
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Affiliation(s)
- Jing Dai
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Daria Madeeva
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Vincent Hayes
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
- Departments of Pathology and Laboratory Medicine and Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Hyun Sook Ahn
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
| | - Valerie Tutwiler
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, PA
| | | | - Douglas B Cines
- Departments of Pathology and Laboratory Medicine and Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Mortimer Poncz
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Lubica Rauova
- Division of Hematology, Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA
- Department of Pediatrics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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