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Clerici B, Pontisso E, Aloise C, Peroni B, Perricone R, Pisetta C, Scavone M, Birocchi S, Podda GM. Thrombosis and Bleeding in Patients with Vaccine-Induced Immune Thrombotic Thrombocytopenia: A Systematic Review of Published Cases. Thromb Haemost 2024; 124:423-431. [PMID: 38109906 DOI: 10.1055/s-0043-1777134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
INTRODUCTION Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a highly prothrombotic reaction to COVID-19 (coronavirus disease 2019) adenoviral vector vaccines. Its distinct bleeding and thrombotic patterns compared with other platelet consumptive disorders remain unclear. METHODS We performed a systematic review of the literature (PubMed and Embase) up to July 31, 2022, including case reports and case series providing nonaggregate data of VITT patients. Accurate VITT diagnosis required fulfillment of the following criteria: (1) endorsement by the authors, (2) consistent vaccine type and timing, (3) presence of thrombocytopenia and thrombosis, (4) detection of anti-platelet factor 4 antibodies. Data are presented as frequencies with 95% confidence intervals (CIs) calculated with the exact binomial method. RESULTS We retrieved 143 eligible studies, describing 366 patients. Of 647 thrombotic events, 53% (95% CI: 49-56) were venous thromboses at unusual sites and 30% (95% CI: 27-34) were cerebral venous sinus thromboses (CVSTs). The ratio of venous-to-arterial events was 4.1. Thromboses in most sites were associated with at least another thrombotic event, with the exception of CVST and CNS arterial thrombosis (isolated in 49 and 39% of cases, respectively). Bleeding occurred in 36% (95% CI: 31-41) of patients; 68% (95% CI: 59-75) of bleeding events were intracranial hemorrhages (ICHs). Overall mortality was 24% (95% CI: 19-29), and 77% (95% CI: 58-90) in patients with isolated CVST complicated by ICH. CONCLUSION VITT displays a venous-to-arterial thrombosis ratio comparable to heparin-induced thrombocytopenia. However, VITT is characterized by a higher prevalence of CVST and ICH, which contribute to the increased bleeding frequency and mortality.
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Affiliation(s)
- Bianca Clerici
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Eleonora Pontisso
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Chiara Aloise
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Benedetta Peroni
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Rosaria Perricone
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Chiara Pisetta
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Mariangela Scavone
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Simone Birocchi
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
| | - Gian Marco Podda
- Dipartimento di Scienze della Salute, Università degli Studi di Milano, Struttura Complessa di Medicina Generale II, Ospedale San Paolo, Milano, Italy
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van der Neut Kolfschoten M, Inganäs H, Perez-Peinado C, Calado da Silva Freire J, Melchers JM, van Dijk N, Przeradzka M, Kourkouta E, van Manen D, Vellinga J, Custers J, Bos R. Biophysical studies do not reveal direct interactions between human PF4 and Ad26.COV2.S vaccine. J Thromb Haemost 2024; 22:1046-1055. [PMID: 38159648 DOI: 10.1016/j.jtha.2023.12.020] [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: 10/09/2023] [Revised: 12/12/2023] [Accepted: 12/17/2023] [Indexed: 01/03/2024]
Abstract
BACKGROUND COVID-19 vaccines have been widely used to control the SARS-CoV-2 pandemic. In individuals receiving replication-incompetent, adenovirus vector-based COVID-19 vaccines (eg, ChAdOx1 nCoV-19 [AstraZeneca] or Ad26.COV2.S [Johnson & Johnson/Janssen] vaccines), a very rare but serious adverse reaction has been reported and described as vaccine-induced immune thrombotic thrombocytopenia (VITT). The exact mechanism of VITT following Ad26.COV2.S vaccination is under investigation. Antibodies directed against human platelet factor 4 (PF4) are considered critical in the pathogenesis of VITT, suggesting similarities with heparin-induced thrombocytopenia. It has been postulated that components of these vaccines mimic the role of heparin by binding to PF4, triggering production of these anti-PF4 antibodies. OBJECTIVES This study aimed to investigate the potential interaction between human PF4 and Ad26.COV2.S vaccine using several biophysical techniques. METHODS Direct interaction of PF4 with Ad26.COV2.S vaccine was investigated using dynamic light scattering, biolayer interferometry, and surface plasmon resonance. For both biosensing methods, the Ad26.COV2.S vaccine was immobilized to the sensor surface and PF4 was used as analyte. RESULTS No direct interactions between PF4 and Ad26.COV2.S vaccine could be detected using dynamic light scattering and biolayer interferometry. Surface plasmon resonance technology was shown to be unsuitable to investigate these types of interactions. CONCLUSION Our findings make it very unlikely that direct binding of PF4 to Ad26.COV2.S vaccine or components thereof is driving the onset of VITT, although the occurrence of such interactions after immunization (potentially facilitated by unknown plasma or cellular factors) cannot be excluded. Further research is warranted to improve the understanding of the full mechanism of this adverse reaction.
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Affiliation(s)
| | - Hanna Inganäs
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | | | | | - Jelle M Melchers
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | - Nelie van Dijk
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | | | - Eleni Kourkouta
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | - Danielle van Manen
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | - Jort Vellinga
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | - Jerome Custers
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands
| | - Rinke Bos
- Janssen Vaccines & Prevention B.V., Leiden, South Holland, The Netherlands.
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Zhang Y, Bissola AL, Treverton J, Hack M, Lychacz M, Kwok S, Arnold A, Nazy I. Vaccine-Induced Immune Thrombotic Thrombocytopenia: Clinicopathologic Features and New Perspectives on Anti-PF4 Antibody-Mediated Disorders. J Clin Med 2024; 13:1012. [PMID: 38398325 PMCID: PMC10889051 DOI: 10.3390/jcm13041012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 01/29/2024] [Accepted: 02/07/2024] [Indexed: 02/25/2024] Open
Abstract
INTRODUCTION Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare yet severe adverse complication first identified during the global vaccination effort against SARS-CoV-2 infection, predominantly observed following administration of the ChAdOx1-S (Oxford-AstraZeneca) and Ad26.CoV2.S (Johnson & Johnson/Janssen) adenoviral vector-based vaccines. Unlike other anti-platelet factor 4 (PF4) antibody-mediated disorders, such as heparin-induced thrombocytopenia (HIT), VITT arises with the development of platelet-activating anti-PF4 antibodies 4-42 days post-vaccination, typically featuring thrombocytopenia and thrombosis at unusual sites. AIM To explore the unique properties, pathogenic mechanisms, and long-term persistence of VITT antibodies in patients, in comparison with other anti-PF4 antibody-mediated disorders. DISCUSSION This review highlights the complexity of VITT as it differs in antibody behavior and clinical presentation from other anti-PF4-mediated disorders, including the high incidence rate of cerebral venous sinus thrombosis (CVST) and the persistence of anti-PF4 antibodies, necessitating a re-evaluation of long-term patient care strategies. The nature of VITT antibodies and the underlying mechanisms triggering their production remain largely unknown. CONCLUSION The rise in awareness and subsequent prompt recognition of VITT is paramount in reducing mortality. As vaccination campaigns continue, understanding the role of adenoviral vector-based vaccines in VITT antibody production is crucial, not only for its immediate clinical implications, but also for developing safer vaccines in the future.
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Affiliation(s)
- Yi Zhang
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (Y.Z.); (J.T.); (M.H.); (S.K.)
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
| | - Anna-Lise Bissola
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Jared Treverton
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (Y.Z.); (J.T.); (M.H.); (S.K.)
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
| | - Michael Hack
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (Y.Z.); (J.T.); (M.H.); (S.K.)
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
| | - Mark Lychacz
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
| | - Sarah Kwok
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (Y.Z.); (J.T.); (M.H.); (S.K.)
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
| | - Addi Arnold
- Department of Pathology and Laboratory Medicine, Western University, London, ON N6A 5A5, Canada;
| | - Ishac Nazy
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON L8S 4K1, Canada; (Y.Z.); (J.T.); (M.H.); (S.K.)
- Michael G. DeGroote Centre for Transfusion Research, McMaster University, Hamilton, ON L8S 4K1, Canada; (A.-L.B.); (M.L.)
- Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8S 4K1, Canada
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Wang JJ, van der Neut Kolfschoten M, Rutten L, Armour B, Tan CW, Chataway T, Bos R, Koornneef A, Abeywickrema P, Kapur R, Porcelijn L, Khalifa M, Sadi A, Bouchier P, Kourkouta E, Perkasa A, Kwaks T, Zahn R, Solforosi L, Gordon TP. Characterization of reverse-engineered anti-PF4 stereotypic antibodies derived from serum of patients with VITT. Blood 2024; 143:370-374. [PMID: 37976451 DOI: 10.1182/blood.2023021307] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Revised: 10/26/2023] [Accepted: 10/31/2023] [Indexed: 11/19/2023] Open
Affiliation(s)
- Jing Jing Wang
- Department of Immunology, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Department of Immunology, SA Pathology, Flinders Medical Centre, Bedford Park, SA, Australia
| | | | - Lucy Rutten
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Bridie Armour
- Department of Immunology, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Department of Immunology, SA Pathology, Flinders Medical Centre, Bedford Park, SA, Australia
| | - Chee Wee Tan
- Department of Medicine, Faculty of Health and Medical Sciences, University of Adelaide, Adelaide, SA, Australia
- Department of Hematology, SA Pathology, Adelaide, SA, Australia
- Department of Hematology, Royal Adelaide Hospital, Central Area Local Health Network, Adelaide, SA, Australia
| | - Tim Chataway
- Flinders Proteomics Facility, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
| | - Rinke Bos
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | - Pravien Abeywickrema
- Structural & Protein Sciences, Janssen Research and Development, Spring House, PA
| | - Rick Kapur
- Sanquin Research, Department of Experimental Immunohematology, and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Leendert Porcelijn
- Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, The Netherlands
| | - Midia Khalifa
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Ava Sadi
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | | | - Aditya Perkasa
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Ted Kwaks
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Roland Zahn
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | - Tom P Gordon
- Department of Immunology, College of Medicine and Public Health, Flinders University, Bedford Park, SA, Australia
- Department of Immunology, SA Pathology, Flinders Medical Centre, Bedford Park, SA, Australia
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Li L, Stegner D. Immunothrombosis versus thrombo-inflammation: platelets in cerebrovascular complications. Res Pract Thromb Haemost 2024; 8:102344. [PMID: 38433977 PMCID: PMC10907225 DOI: 10.1016/j.rpth.2024.102344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/22/2023] [Accepted: 01/30/2024] [Indexed: 03/05/2024] Open
Abstract
A State-of-the Art lecture titled "Thrombo-Neuroinflammatory Disease" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. First, we would like to advocate for discrimination between immunothrombosis and thrombo-inflammation, as immunothrombosis describes an overshooting inflammatory reaction that results in detrimental thrombotic activity. In contrast, thrombo-inflammation describes the interplay of platelets and coagulation with the immunovascular system, resulting in the recruitment of immune cells and loss of barrier function (hence, hallmarks of inflammation). Both processes can be observed in the brain, with cerebral venous thrombosis being a prime example of immunothrombosis, while infarct progression in response to ischemic stroke is a paradigmatic example of thrombo-inflammation. Here, we review the pathomechanisms underlying cerebral venous thrombosis and ischemic stroke from a platelet-centric perspective and discuss translational implications. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.
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Affiliation(s)
- Lexiao Li
- Julius-Maximilians-Universität Würzburg, Rudolf Virchow Center for Integrative and Translational Bioimaging, Würzburg, Germany
- University Hospital Würzburg, Institute of Experimental Biomedicine, Würzburg, Germany
| | - David Stegner
- Julius-Maximilians-Universität Würzburg, Rudolf Virchow Center for Integrative and Translational Bioimaging, Würzburg, Germany
- University Hospital Würzburg, Institute of Experimental Biomedicine, Würzburg, Germany
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6
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Raadsen MP, Visser C, Lavell AHA, van de Munckhof AAGA, Coutinho JM, de Maat MPM, GeurtsvanKessel CH, Bomers MK, Haagmans BL, van Gorp ECM, Porcelijn L, Kruip MJHA. Transient Autoreactive PF4 and Antiphospholipid Antibodies in COVID-19 Vaccine Recipients. Vaccines (Basel) 2023; 11:1851. [PMID: 38140254 PMCID: PMC10747426 DOI: 10.3390/vaccines11121851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 12/05/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare autoimmune condition associated with recombinant adenovirus (rAV)-based COVID-19 vaccines. It is thought to arise from autoantibodies targeting platelet factor 4 (aPF4), triggered by vaccine-induced inflammation and the formation of neo-antigenic complexes between PF4 and the rAV vector. To investigate the specific induction of aPF4 by rAV-based vaccines, we examined sera from rAV vaccine recipients (AZD1222, AD26.COV2.S) and messenger RNA (mRNA) based (mRNA-1273, BNT162b2) COVID-19 vaccine recipients. We compared the antibody fold change (FC) for aPF4 and for antiphospholipid antibodies (aPL) of rAV to mRNA vaccine recipients. We combined two biobanks of Dutch healthcare workers and matched rAV-vaccinated individuals to mRNA-vaccinated controls, based on age, sex and prior history of COVID-19 (AZD1222: 37, Ad26.COV2.S: 35, mRNA-1273: 47, BNT162b2: 26). We found no significant differences in aPF4 FCs after the first (0.99 vs. 1.08, mean difference (MD) = -0.11 (95% CI -0.23 to 0.057)) and second doses of AZD1222 (0.99 vs. 1.10, MD = -0.11 (95% CI -0.31 to 0.10)) and after a single dose of Ad26.COV2.S compared to mRNA-based vaccines (1.01 vs. 0.99, MD = 0.026 (95% CI -0.13 to 0.18)). The mean FCs for the aPL in rAV-based vaccine recipients were similar to those in mRNA-based vaccines. No correlation was observed between post-vaccination aPF4 levels and vaccine type (mean aPF difference -0.070 (95% CI -0.14 to 0.002) mRNA vs. rAV). In summary, our study indicates that rAV and mRNA-based COVID-19 vaccines do not substantially elevate aPF4 levels in healthy individuals.
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Affiliation(s)
- Matthijs P. Raadsen
- Department of Viroscience, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (M.P.R.); (C.H.G.); (B.L.H.); (E.C.M.v.G.)
| | - Chantal Visser
- Department of Hematology, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (C.V.); (M.P.M.d.M.)
| | - A. H. Ayesha Lavell
- Department of Internal Medicine, Amsterdam UMC Location Vrije Universiteit Amsterdam, Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; (A.H.A.L.); (M.K.B.)
- Amsterdam Institute for Infection & Immunity, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Anita A. G. A. van de Munckhof
- Department of Neurology, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (A.A.G.A.v.d.M.); (J.M.C.)
| | - Jonathan M. Coutinho
- Department of Neurology, Amsterdam UMC Location University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands; (A.A.G.A.v.d.M.); (J.M.C.)
| | - Moniek P. M. de Maat
- Department of Hematology, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (C.V.); (M.P.M.d.M.)
| | - Corine H. GeurtsvanKessel
- Department of Viroscience, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (M.P.R.); (C.H.G.); (B.L.H.); (E.C.M.v.G.)
| | | | - Marije K. Bomers
- Department of Internal Medicine, Amsterdam UMC Location Vrije Universiteit Amsterdam, Boelelaan 1117, 1081 HV Amsterdam, The Netherlands; (A.H.A.L.); (M.K.B.)
- Amsterdam Institute for Infection & Immunity, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Bart L. Haagmans
- Department of Viroscience, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (M.P.R.); (C.H.G.); (B.L.H.); (E.C.M.v.G.)
| | - Eric C. M. van Gorp
- Department of Viroscience, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (M.P.R.); (C.H.G.); (B.L.H.); (E.C.M.v.G.)
| | - Leendert Porcelijn
- Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Plesmanlaan 125, 1066 CX Amsterdam, The Netherlands;
| | - Marieke J. H. A. Kruip
- Department of Hematology, Erasmus MC, University Medical Center Rotterdam, 3000 CA Rotterdam, The Netherlands; (C.V.); (M.P.M.d.M.)
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Warkentin TE. Autoimmune Heparin-Induced Thrombocytopenia. J Clin Med 2023; 12:6921. [PMID: 37959386 PMCID: PMC10649402 DOI: 10.3390/jcm12216921] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 11/15/2023] Open
Abstract
Autoimmune thrombocytopenia (aHIT) is a severe subtype of heparin-induced thrombocytopenia (HIT) with atypical clinical features caused by highly pathological IgG antibodies ("aHIT antibodies") that activate platelets even in the absence of heparin. The clinical features of aHIT include: the onset or worsening of thrombocytopenia despite stopping heparin ("delayed-onset HIT"), thrombocytopenia persistence despite stopping heparin ("persisting" or "refractory HIT"), or triggered by small amounts of heparin (heparin "flush" HIT), most cases of fondaparinux-induced HIT, and patients with unusually severe HIT (e.g., multi-site or microvascular thrombosis, overt disseminated intravascular coagulation [DIC]). Special treatment approaches are required. For example, unlike classic HIT, heparin cessation does not result in de-escalation of antibody-induced hemostasis activation, and thus high-dose intravenous immunoglobulin (IVIG) may be indicated to interrupt aHIT-induced platelet activation; therapeutic plasma exchange may be required if high-dose IVIG is ineffective. Also, aHIT patients are at risk for treatment failure with (activated partial thromboplastin time [APTT]-adjusted) direct thrombin inhibitor (DTI) therapy (argatroban, bivalirudin), either because of APTT confounding (where aHIT-associated DIC and resulting APTT prolongation lead to systematic underdosing/interruption of DTI therapy) or because DTI inhibits thrombin-induced protein C activation. Most HIT laboratories do not test for aHIT antibodies, contributing to aHIT under-recognition.
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Affiliation(s)
- Theodore E. Warkentin
- Department of Pathology and Molecular Medicine and Department of Medicine, Michael G. DeGroote School of Medicine, McMaster University, Hamilton, ON L8N 3Z5, Canada; ; Tel.: +1-(905)-527-0271 (ext. 46139)
- Service of Benign Hematology, Hamilton Health Sciences (General Site), Hamilton, ON L8L 2X2, Canada
- Transfusion Medicine, Hamilton Regional Laboratory Medicine Program, Hamilton, ON L8L 2X2, Canada
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