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Meier RT, Porcelijn L, Hofstede-van Egmond S, Caram-Deelder C, Coutinho JM, Henskens YMC, Kruip MJHA, Stroobants AK, Zwaginga JJ, van der Schoot CE, de Haas M, Kapur R. Antibodies against Platelet Glycoproteins in Clinically Suspected VITT Patients. Antibodies (Basel) 2024; 13:35. [PMID: 38804303 PMCID: PMC11130846 DOI: 10.3390/antib13020035] [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: 01/24/2024] [Revised: 04/02/2024] [Accepted: 04/16/2024] [Indexed: 05/29/2024] Open
Abstract
Vaccine-induced thrombotic thrombocytopenia (VITT) is a rare but severe complication following COVID-19 vaccination, marked by thrombocytopenia and thrombosis. Analogous to heparin-induced thrombocytopenia (HIT), VITT shares similarities in anti-platelet factor 4 (PF4) IgG-mediated platelet activation via the FcγRIIa. To investigate the involvement of platelet-antibodies in VITT, we analyzed the presence of platelet-antibodies directed against glycoproteins (GP)IIb/IIIa, GPV and GPIb/IX in the serum of 232 clinically suspected VITT patients determined based on (suspicion of) occurrence of thrombocytopenia and/or thrombosis in relation to COVID-19 vaccination. We found that 19% of clinically suspected VITT patients tested positive for anti-platelet GPs: 39%, 32% and 86% patients tested positive for GPIIb/IIIa, GPV and GPIb/IX, respectively. No HIT-like VITT patients (with thrombocytopenia and thrombosis) tested positive for platelet-antibodies. Therefore, it seems unlikely that platelet-antibodies play a role in HIT-like anti-PF4-mediated VITT. Platelet-antibodies were predominantly associated with the occurrence of thrombocytopenia. We found no association between the type of vaccination (adenoviral vector vaccine versus mRNA vaccine) or different vaccines (ChAdOx1 nCoV-19, Ad26.COV2.S, mRNA-1273, BTN162b2) and the development of platelet-antibodies. It is essential to conduct more research on the pathophysiology of VITT, to improve diagnostic approaches and identify preventive and therapeutic strategies.
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Affiliation(s)
- Romy T. Meier
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, 1066 CX Amsterdam, The Netherlands; (R.T.M.); (C.E.v.d.S.)
| | - Leendert Porcelijn
- Sanquin Diagnostic Services, Department of Immunohematology Diagnostics, Sanquin, 1066 CX Amsterdam, The Netherlands; (L.P.); (S.H.-v.E.); (M.d.H.)
| | - Suzanne Hofstede-van Egmond
- Sanquin Diagnostic Services, Department of Immunohematology Diagnostics, Sanquin, 1066 CX Amsterdam, The Netherlands; (L.P.); (S.H.-v.E.); (M.d.H.)
| | - Camila Caram-Deelder
- Department of Clinical Epidemiology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
| | | | - Yvonne M. C. Henskens
- Central Diagnostic Laboratory, Maastricht University Medical Centre+, 6229 HX Maastricht, The Netherlands;
| | - Marieke J. H. A. Kruip
- Department of Haematology, Erasmus MC, Erasmus University Medical Center, 3015 CN Rotterdam, The Netherlands;
| | - An K. Stroobants
- Department of Clinical Chemistry, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands;
| | - Jaap J. Zwaginga
- Department of Hematology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
| | - C. Ellen van der Schoot
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, 1066 CX Amsterdam, The Netherlands; (R.T.M.); (C.E.v.d.S.)
| | - Masja de Haas
- Sanquin Diagnostic Services, Department of Immunohematology Diagnostics, Sanquin, 1066 CX Amsterdam, The Netherlands; (L.P.); (S.H.-v.E.); (M.d.H.)
- Department of Hematology, Leiden University Medical Center, 2333 ZA Leiden, The Netherlands;
| | - Rick Kapur
- Department of Experimental Immunohematology, Sanquin Research and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, 1066 CX Amsterdam, The Netherlands; (R.T.M.); (C.E.v.d.S.)
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Kashiwagi H, Kuwana M, Murata M, Shimada N, Takafuta T, Yamanouchi J, Kato H, Hato T, Tomiyama Y. Reference guide for the diagnosis of adult primary immune thrombocytopenia, 2023 edition. Int J Hematol 2024; 119:1-13. [PMID: 37957517 PMCID: PMC10770234 DOI: 10.1007/s12185-023-03672-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 09/29/2023] [Accepted: 10/02/2023] [Indexed: 11/15/2023]
Abstract
Primary immune thrombocytopenia (ITP) is an autoimmune disorder characterized by isolated thrombocytopenia due to accelerated platelet destruction and impaired platelet production. Diagnosis of ITP is still challenging because ITP has been diagnosed by exclusion. Exclusion of thrombocytopenia due to bone marrow failure is especially important in Japan because of high prevalence of aplastic anemia compared to Western countries. Hence, we propose a new diagnostic criteria involving the measurement of plasma thrombopoietin (TPO) levels and percentage of immature platelet fraction (RP% or IPF%); 1) isolated thrombocytopenia with no morphological evidence of dysplasia in any blood cell type in a blood smear, 2) normal or slightly increased plasma TPO level (< cutoff), 3) elevated RP% or IPF% (> upper limit of normal), and 4) absence of other conditions that potentially cause thrombocytopenia including secondary ITP. A diagnosis of ITP is made if conditions 1-4 are all met. Cases in which criterion 2 or 3 is not met or unavailable are defined as "possible ITP," and diagnosis of ITP can be made mainly by typical clinical course. These new criteria enable us to clearly differentiate ITP from aplastic anemia and other forms of hypoplastic thrombocytopenia and can be highly useful in clinical practice for avoiding unnecessary bone marrow examination as well as for appropriate selection of treatments.
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Affiliation(s)
- Hirokazu Kashiwagi
- Department of Blood Transfusion, Osaka University Hospital, Suita, Osaka, 565-0871, 2-15, Yamadaoka, Japan.
| | - Masataka Kuwana
- Department of Allergy and Rheumatology, Nippon Medical School Graduate School of Medicine, Tokyo, Japan
| | - Mitsuru Murata
- Center for Clinical Medical Research, International University of Health and Welfare, Ohtawara, Tochigi, Japan
| | - Naoki Shimada
- Center for Basic Medical Research, International University of Health and Welfare, Ohtawara, Tochigi, Japan
| | - Toshiro Takafuta
- Department of Internal Medicine, Hiroshima City Funairi Citizens Hospital, Hiroshima, Hiroshima, Japan
| | - Jun Yamanouchi
- Division of Blood Transfusion and Cell Therapy, Ehime University Hospital, Toon, Ehime, Japan
| | - Hisashi Kato
- Department of Hematology and Oncology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
| | - Takaaki Hato
- Japanese Red Cross Ehime Blood Center, Matsuyama, Ehime, Japan
| | - Yoshiaki Tomiyama
- Department of Hematology and Oncology, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan
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3
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Zheng SS, Ahmadi Z, Leung HHL, Wong R, Yan F, Perdomo JS, Chong BH. Antiplatelet antibody predicts platelet desialylation and apoptosis in immune thrombocytopenia. Haematologica 2022; 107:2195-2205. [PMID: 35199503 PMCID: PMC9425302 DOI: 10.3324/haematol.2021.279751] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 02/18/2021] [Indexed: 11/09/2022] Open
Abstract
Immune thrombocytopenia (ITP) is a bleeding disorder caused by dysregulated B- and T- cell functions, which lead to platelet destruction. A well-recognized mechanism of ITP pathogenesis involves anti-platelet and anti-megakaryocyte antibodies recognizing membrane glycoprotein (GP) complexes, mainly GPIb/IX and GPIIb/IIIa. In addition to the current view of phagocytosis of the opsonised platelets by splenic and hepatic macrophages via their Fc γ receptors, antibodyinduced platelet desialylation and apoptosis have also been reported to contribute to ITP pathogenesis. Nevertheless, the relationship between the specific thrombocytopenic mechanisms and various types of anti-platelet antibodies has not been established. In order to ascertain such association, we used sera from 61 ITP patients and assessed the capacity of anti-platelet antibodies to induce neuraminidase 1 (NEU1) surface expression, RCA-1 lectin binding and loss of mitochondrial inner membrane potential on donors' platelets. Sera from ITP patients with detectable antibodies caused significant platelet desialylation and apoptosis. Anti-GPIIb/IIIa antibodies appeared more capable of causing NEU1 surface translocation while anti-GPIb/IX complex antibodies resulted in a higher degree of platelet apoptosis. In ITP patients with anti-GPIIb/IIIa antibodies, both desialylation and apoptosis were dependent on FcγRIIa signaling rather than platelet activation. Finally, we confirmed in a murine model of ITP that destruction of human platelets induced by anti-GPIIb/IIIa antibodies can be prevented with the NEU1 inhibitor oseltamivir. A collaborative clinical trial is warranted to investigate the utility of oseltamivir in the treatment of ITP.
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Affiliation(s)
- Shiying Silvia Zheng
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney, Australia; Department of Haematology, St. George Hospital, Kogarah, New South Wales.
| | - Zohra Ahmadi
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney
| | - Halina Hoi Laam Leung
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney
| | - Rose Wong
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney, Australia; Department of Haematology, St. George Hospital, Kogarah, New South Wales
| | - Feng Yan
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney, Australia; Department of Haematology, St. George Hospital, Kogarah, New South Wales
| | - Jose Sail Perdomo
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney
| | - Beng Hock Chong
- Haematology Research Unit, St. George and Sutherland Clinical School, University of New South Wales, Sydney, Australia; Department of Haematology, St. George Hospital, Kogarah, New South Wales
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Potential Diagnostic Approaches for Prediction of Therapeutic Responses in Immune Thrombocytopenia. J Clin Med 2021; 10:jcm10153403. [PMID: 34362187 PMCID: PMC8347743 DOI: 10.3390/jcm10153403] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/27/2021] [Accepted: 07/28/2021] [Indexed: 12/13/2022] Open
Abstract
Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder in which, via unresolved mechanisms, platelets and megakaryocytes (MKs) are targeted by autoantibodies and/or T cells resulting in increased platelet destruction and impairment of MK function. Over the years, several therapeutic modalities have become available for ITP, however, therapeutic management has proven to be very challenging in several cases. Patients refractory to treatment can develop a clinically worsening disease course, treatment-induced toxicities and are predisposed to development of potentially life-endangering bleedings. It is therefore of critical importance to timely identify potential refractory patients, for which novel diagnostic approaches are urgently needed in order to monitor and predict specific therapeutic responses. In this paper, we propose promising diagnostic investigations into immune functions and characteristics in ITP, which may potentially be exploited to help predict platelet count responses and thereby distinguish therapeutic responders from non-responders. This importantly includes analysis of T cell homeostasis, which generally appears to be disturbed in ITP due to decreased and/or dysfunctional T regulatory cells (Tregs) leading to loss of immune tolerance and initiation/perpetuation of ITP, and this may be normalized by several therapeutic modalities. Additional avenues to explore in possible prediction of therapeutic responses include examination of platelet surface sialic acids, platelet apoptosis, monocyte surface markers, B regulatory cells and platelet microparticles. Initial studies have started evaluating these markers in relation to response to various treatments including glucocorticosteroids (GCs), intravenous immunoglobulins (IVIg) and/or thrombopoietin receptor agonists (TPO-RA), however, further studies are highly warranted. The systematic molecular analysis of a broad panel of immune functions may ultimately help guide and improve personalized therapeutic management in ITP.
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Semple JW, Rebetz J, Maouia A, Kapur R. An update on the pathophysiology of immune thrombocytopenia. Curr Opin Hematol 2021; 27:423-429. [PMID: 32868673 DOI: 10.1097/moh.0000000000000612] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
: Immune thrombocytopenia (ITP) is an autoimmune bleeding disorder mediated by antiplatelet autoantibodies and antigen-specific T cells that either destroy platelets peripherally in the spleen or impair platelet production in the bone marrow. There have been a plethora of publications relating to the pathophysiology of ITP and since January of 2019, at least 50 papers have been published on ITP pathophysiology. PURPOSE OF REVIEW To summarize the literature relating to the pathophysiology of ITP including the working mechanisms of therapies, T-cell and B-cell physiology, protein/RNA/DNA biochemistry, and animal models in an attempt to unify the perceived abnormal immune processes. RECENT FINDINGS The most recent pathophysiologic irregularities associated with ITP relate to abnormal T-cell responses, particularly, defective T regulatory cell activity and how therapeutics can restore these responses. The robust literature on T cells in ITP points to the notion that ITP is a disease initiated by faulty self-tolerance mechanisms very much like that of other organ-specific autoimmune diseases. There is also a large literature on new and existing animal models of ITP and these will be discussed. It appears that understanding how to specifically modulate T cells in patients with ITP will undoubtedly lead to effective antigen-specific therapeutics. CONCLUSIONS ITP is predominately a T cell disorder which leads to a breakdown in self tolerance mechanisms and allows for the generation of anti-platelet autoantibodies and T cells. Novel therapeutics that target T cells may be the most effective way to perhaps cure this disorder.
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Affiliation(s)
- John W Semple
- Division of Hematology and Transfusion Medicine, Lund University.,Clinical Immunology and Transfusion Medicine, Office of Medical Services, Region Skåne, Lund, Sweden
| | - Johan Rebetz
- Division of Hematology and Transfusion Medicine, Lund University
| | - Amal Maouia
- Division of Hematology and Transfusion Medicine, Lund University
| | - Rick Kapur
- Sanquin Research, Department of Experimental Immunohematology, Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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Immune Thrombocytopenia: Recent Advances in Pathogenesis and Treatments. Hemasphere 2021; 5:e574. [PMID: 34095758 PMCID: PMC8171374 DOI: 10.1097/hs9.0000000000000574] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 04/08/2021] [Indexed: 11/26/2022] Open
Abstract
Immune thrombocytopenia (ITP) is a rare autoimmune disease due to both a peripheral destruction of platelets and an inappropriate bone marrow production. Although the primary triggering factors of ITP remain unknown, a loss of immune tolerance-mostly represented by a regulatory T-cell defect-allows T follicular helper cells to stimulate autoreactive splenic B cells that differentiate into antiplatelet antibody-producing plasma cells. Glycoprotein IIb/IIIa is the main target of antiplatelet antibodies leading to platelet phagocytosis by splenic macrophages, through interactions with Fc gamma receptors (FcγRs) and complement receptors. This allows macrophages to activate autoreactive T cells by their antigen-presenting functions. Moreover, the activation of the classical complement pathway participates to platelet opsonization and also to their destruction by complement-dependent cytotoxicity. Platelet destruction is also mediated by a FcγR-independent pathway, involving platelet desialylation that favors their binding to the Ashwell-Morell receptor and their clearance in the liver. Cytotoxic T cells also contribute to ITP pathogenesis by mediating cytotoxicity against megakaryocytes and peripheral platelets. The deficient megakaryopoiesis resulting from both the humoral and the cytotoxic immune responses is sustained by inappropriate levels of thrombopoietin, the major growth factor of megakaryocytes. The better understanding of ITP pathogenesis has provided important therapeutic advances. B cell-targeting therapies and thrombopoietin-receptor agonists (TPO-RAs) have been used for years. New emerging therapeutic strategies that inhibit FcγR signaling, the neonatal Fc receptor or the classical complement pathway, will deeply modify the management of ITP in the near future.
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A modern reassessment of glycoprotein-specific direct platelet autoantibody testing in immune thrombocytopenia. Blood Adv 2021; 4:9-18. [PMID: 31891657 DOI: 10.1182/bloodadvances.2019000868] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/21/2019] [Indexed: 12/30/2022] Open
Abstract
Platelet autoantibody (PA) testing has previously shown poor sensitivity for immune thrombocytopenia (ITP) diagnosis, but no previous study used both 2011 American Society of Hematology (ASH) guidelines for ITP diagnosis and 2012 International Society on Thrombosis and Haemostasis (ISTH) PA testing recommendations. We therefore performed a comprehensive retrospective study of PA testing in adult patients with ITP strictly applying these criteria. Of 986 PA assays performed, 485 assays in 368 patients met criteria and were included. Sensitivity and specificity of a positive test result for diagnosis of active ITP (n = 228 patients) were 90% and 78%, respectively. Sensitivity and specificity of a negative test result for clinical remission (n = 61 assays) were 87% and 91%. Antibodies against both glycoprotein IIb (GPIIb)/IIIa and GPIb/IX were required for the presence of antibodies against GPIa/IIa in patients with ITP. Logistic regression analysis revealed that more positive autoantibodies predicted more severe disease (relative to nonsevere ITP, relative risk ratio for severe ITP and refractory ITP was 2.27 [P < .001] and 3.09 [P < .001], respectively, per additional autoantibody); however, serologic testing did not meaningfully predict treatment response to glucocorticoids, intravenous immunoglobulin, or thrombopoietin receptor agonists. Sixty-four patients with ITP had multiple PA assays performed longitudinally: all 10 patients achieving remission converted from positive to negative serologic results, and evidence for epitope spreading was observed in 35% of patients with ongoing active disease. In conclusion, glycoprotein-specific direct PA testing performed using ISTH recommendations in patients meeting ASH diagnostic criteria is sensitive and specific for ITP diagnosis and reliably confirms clinical remission. More glycoproteins targeted by autoantibodies predicts for more severe disease.
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Karakas D, Xu M, Ni H. GPIbα is the driving force of hepatic thrombopoietin generation. Res Pract Thromb Haemost 2021; 5:e12506. [PMID: 33977209 PMCID: PMC8105161 DOI: 10.1002/rth2.12506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 12/25/2022] Open
Abstract
Thrombopoietin (TPO), a glycoprotein hormone produced predominantly in the liver, plays important roles in the hematopoietic stem cell (HSC) niche, and is essential for megakaryopoiesis and platelet generation. Long-standing understanding proposes that TPO is constitutively produced by hepatocytes, and levels are fine-tuned through platelet and megakaryocyte internalization/degradation via the c-Mpl receptor. However, in immune thrombocytopenia (ITP) and several other diseases, TPO levels are inconsistent with this theory. Recent studies showed that platelets, besides their TPO clearance, can induce TPO production in the liver. Our group also accidentally discovered that platelet glycoprotein (GP) Ibα is required for platelet-mediated TPO generation, which is underscored in both GPIbα-/- mice and patients with Bernard-Soulier syndrome. This review will introduce platelet versatilities and several new findings in hemostasis and platelet consumption but focus on its roles in TPO regulation. The implications of these new discoveries in hematopoiesis and the HSC niche, particularly in ITP, will be discussed.
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Affiliation(s)
- Danielle Karakas
- Department of Laboratory Medicine and PathobiologyUniversity of TorontoTorontoONCanada
- Toronto Platelet Immunobiology GroupTorontoONCanada
- Department of Laboratory MedicineKeenan Research Centre for Biomedical ScienceSt. Michael’s HospitalTorontoONCanada
| | - Miao Xu
- Department of HematologyQilu HospitalCheeloo College of MedicineShandong UniversityJinanChina
| | - Heyu Ni
- Department of Laboratory Medicine and PathobiologyUniversity of TorontoTorontoONCanada
- Toronto Platelet Immunobiology GroupTorontoONCanada
- Department of Laboratory MedicineKeenan Research Centre for Biomedical ScienceSt. Michael’s HospitalTorontoONCanada
- Canadian Blood Services Centre for InnovationTorontoONCanada
- Department of MedicineUniversity of TorontoTorontoONCanada
- Department of PhysiologyUniversity of TorontoTorontoONCanada
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Porcelijn L, Schmidt DE, Oldert G, Hofstede-van Egmond S, Kapur R, Zwaginga JJ, de Haas M. Evolution and Utility of Antiplatelet Autoantibody Testing in Patients with Immune Thrombocytopenia. Transfus Med Rev 2020; 34:258-269. [PMID: 33046350 DOI: 10.1016/j.tmrv.2020.09.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 01/01/2023]
Abstract
To this day, immune thrombocytopenia (ITP) remains a clinical diagnosis made by exclusion of other causes for thrombocytopenia. Reliable detection of platelet autoantibodies would support the clinical diagnosis, but the lack of specificity and sensitivity of the available methods for platelet autoantibody testing limits their value in the diagnostic workup of thrombocytopenia. The introduction of methods for glycoprotein-specific autoantibody detection has improved the specificity of testing and is acceptable for ruling in ITP but not ruling it out as a diagnosis. The sensitivity of these assays varies widely, even between studies using comparable assays. A review of the relevant literature combined with our own laboratory's experience of testing large number of serum and platelet samples makes it clear that this variation can be explained by variations in the characteristics of the tests, including in the glycoprotein-specific monoclonal antibodies, the glycoproteins that are tested, the platelet numbers used in the assay and the cutoff levels for positive and negative results, as well as differences in the tested patient populations. In our opinion, further standardization and optimization of the direct autoantibody detection methods to increase sensitivity without compromising specificity seem possible but will still likely be insufficient to distinguish the often very weak specific autoantibody signals from background signals. Further developments of autoantibody detection methods will therefore be necessary to increase sensitivity to a level acceptable to provide laboratory confirmation of a diagnosis of ITP.
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Affiliation(s)
- Leendert Porcelijn
- Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, the Netherlands.
| | - David E Schmidt
- Sanquin Research, Department of Experimental Immunohematology, Amsterdam and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Gonda Oldert
- Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, the Netherlands
| | | | - Rick Kapur
- Sanquin Research, Department of Experimental Immunohematology, Amsterdam and Landsteiner Laboratory, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands
| | - Jaap Jan Zwaginga
- Department of Immuno-hematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands; Sanquin Research, Center for Clinical Transfusion Research, Leiden, the Netherlands; Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands
| | - Masja de Haas
- Department of Immunohematology Diagnostics, Sanquin Diagnostic Services, Amsterdam, the Netherlands; Sanquin Research, Center for Clinical Transfusion Research, Leiden, the Netherlands; Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, the Netherlands
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Abstract
Platelets, small anucleate cells circulating in the blood, are critical mediators in haemostasis and thrombosis. Interestingly, recent studies demonstrated that platelets contain both pro-inflammatory and anti-inflammatory molecules, equipping platelets with immunoregulatory function in both innate and adaptive immunity. In the context of infectious diseases, platelets are involved in early detection of invading microorganisms and are actively recruited to sites of infection. Platelets exert their effects on microbial pathogens either by direct binding to eliminate or restrict dissemination, or by shaping the subsequent host immune response. Reciprocally, many invading microbial pathogens can directly or indirectly target host platelets, altering platelet count or/and function. In addition, microbial pathogens can impact the host auto- and alloimmune responses to platelet antigens in several immune-mediated diseases, such as immune thrombocytopenia, and fetal and neonatal alloimmune thrombocytopenia. In this review, we discuss the mechanisms that contribute to the bidirectional interactions between platelets and various microbial pathogens, and how these interactions hold relevant implications in the pathogenesis of many infectious diseases. The knowledge obtained from "well-studied" microbes may also help us understand the pathogenesis of emerging microbes, such as SARS-CoV-2 coronavirus.
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Affiliation(s)
- Conglei Li
- Department of Immunology, University of Toronto, Toronto, ON, Canada
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, ON, Canada
| | - June Li
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Canadian Blood Services Centre for Innovation, Toronto, ON, Canada
| | - Heyu Ni
- Toronto Platelet Immunobiology Group, University of Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
- Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Canadian Blood Services Centre for Innovation, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Department of Medicine, University of Toronto, Toronto, ON, Canada
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