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1.
Blood ; 139(10): 1564-1574, 2022 03 10.
Article in English | MEDLINE | ID: covidwho-1736325

ABSTRACT

Cases of de novo immune thrombocytopenia (ITP), including a fatality, following SARS-CoV-2 vaccination in previously healthy recipients led to studying its impact in preexisting ITP. In this study, 4 data sources were analyzed: the Vaccine Adverse Events Reporting System (VAERS) for cases of de novo ITP; a 10-center retrospective study of adults with preexisting ITP receiving SARS-CoV-2 vaccination; and surveys distributed by the Platelet Disorder Support Association (PDSA) and the United Kingdom (UK) ITP Support Association. Seventy-seven de novo ITP cases were identified in VAERS, presenting with median platelet count of 3 [1-9] ×109/L approximately 1 week postvaccination. Of 28 patients with available data, 26 responded to treatment with corticosteroids and/or intravenous immunoglobulin (IVIG), and/or platelet transfusions. Among 117 patients with preexisting ITP who received a SARS-CoV-2 vaccine, 19 experienced an ITP exacerbation (any of: ≥50% decline in platelet count, nadir platelet count <30 × 109/L with >20% decrease from baseline, and/or use of rescue therapy) following the first dose and 14 of 70 after a second dose. Splenectomized persons and those who received 5 or more prior lines of therapy were at highest risk of ITP exacerbation. Fifteen patients received and responded to rescue treatment. In surveys of both 57 PDSA and 43 UK patients with ITP, prior splenectomy was associated with worsened thrombocytopenia. ITP may worsen in preexisting ITP or be identified de novo post-SARS-CoV2 vaccination; both situations responded well to treatment. Proactive monitoring of patients with known ITP, especially those postsplenectomy and with more refractory disease, is indicated.


Subject(s)
COVID-19 Vaccines , COVID-19 , Purpura, Thrombocytopenic, Idiopathic , SARS-CoV-2 , Aged , Aged, 80 and over , Blood Platelets/immunology , Blood Platelets/metabolism , COVID-19/blood , COVID-19/epidemiology , COVID-19/immunology , COVID-19/prevention & control , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/immunology , Female , Humans , Male , Middle Aged , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Purpura, Thrombocytopenic, Idiopathic/epidemiology , Purpura, Thrombocytopenic, Idiopathic/immunology , Retrospective Studies , Risk Factors , SARS-CoV-2/immunology , SARS-CoV-2/metabolism , Splenectomy , United Kingdom/epidemiology
3.
Eur Rev Med Pharmacol Sci ; 26(1): 270-277, 2022 01.
Article in English | MEDLINE | ID: covidwho-1631285

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare new syndrome occurring after the ChAdOx1 nCoV-19 vaccine immunization. Patients with VITT are characterized by a variable clinical presentation, likewise also the outcome of these patients is very variable. Here we report the lung ultrastructural findings in the course of VITT of a 58-year-old male patient. Alveoli were mainly dilated, irregular in shape, and occupied by a reticular network of fibrin, while interalveolar septa appeared thickened. The proliferation of small capillaries gave rise to plexiform structures and pulmonary capillary hemangiomatosis-like features. Near the alveoli occupied by a dense fibrin network, the medium-sized arteries showed a modified wall and an intraluminal thrombus. This scenario looks quite similar to that found during COVID-19, where the lungs suffer from the attack of the antigen-antibodies complexes and the virus respectively. In both diseases, the final outcome is a severe inflammation, activation of the haemostatic system and fibrinolysis.


Subject(s)
/adverse effects , Lung Injury/etiology , Lung Injury/pathology , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Vaccination/adverse effects , COVID-19/prevention & control , Fibrin , Humans , Lung Injury/diagnostic imaging , Lung Injury/immunology , Male , Microscopy, Electron, Scanning , Middle Aged , Parenchymal Tissue/pathology , Purpura, Thrombocytopenic, Idiopathic/diagnosis , Purpura, Thrombocytopenic, Idiopathic/immunology
4.
Blood Coagul Fibrinolysis ; 32(7): 427-433, 2021 Oct 01.
Article in English | MEDLINE | ID: covidwho-1526210

ABSTRACT

Immune thrombocytopenia is a haematological, autoimmune disorder characterized by elevated platelet demolition due to the presence of antiplatelet autoantibodies derived from B cells and to an irregular, deficient process of platelets production in bone marrow. In this review, after a brief presentation of 'old' strategies used nowadays yet, we focused on new drugs used in the treatment of immune thrombocytopenia and their mechanism of action and posology, basing on the last scientific literature. The observation that CoViD-19 can be associated with immune thrombocytopenia is also put in evidence. Particular attention will be dedicated on the concept that the ideal treatment should represent a solution not only for the failure of normal processes of production and survival of platelets, but also it should improve quality of life of patients, with minimum adverse events. Anyway, despite enormous advances of the last years, further investigations are necessary in order to define scrupulously long-term efficacy of new molecules proposed.


Subject(s)
Purpura, Thrombocytopenic, Idiopathic/drug therapy , Aminopyridines/therapeutic use , Antibodies, Monoclonal, Humanized/therapeutic use , COVID-19/complications , COVID-19/immunology , Histocompatibility Antigens Class I , Humans , Immunosuppressive Agents/therapeutic use , Morpholines/therapeutic use , Protein Kinase Inhibitors/therapeutic use , Purpura, Thrombocytopenic, Idiopathic/etiology , Purpura, Thrombocytopenic, Idiopathic/immunology , Pyrimidines/therapeutic use , Receptors, Fc/antagonists & inhibitors , Receptors, Thrombopoietin/agonists , SARS-CoV-2/immunology , Syk Kinase/antagonists & inhibitors , Thiazoles/therapeutic use , Thiophenes/therapeutic use
6.
Int J Mol Sci ; 22(19)2021 Oct 06.
Article in English | MEDLINE | ID: covidwho-1457948

ABSTRACT

Novel coronavirus SARS-CoV-2 has resulted in a global pandemic with worldwide 6-digit infection rates and thousands of death tolls daily. Enormous efforts are undertaken to achieve high coverage of immunization to reach herd immunity in order to stop the spread of SARS-CoV-2 infection. Several SARS-CoV-2 vaccines based on mRNA, viral vectors, or inactivated SARS-CoV-2 virus have been approved and are being applied worldwide. However, the recent increased numbers of normally very rare types of thromboses associated with thrombocytopenia have been reported, particularly in the context of the adenoviral vector vaccine ChAdOx1 nCoV-19 from Astra Zeneca. The statistical prevalence of these side effects seems to correlate with this particular vaccine type, i.e., adenoviral vector-based vaccines, but the exact molecular mechanisms are still not clear. The present review summarizes current data and hypotheses for molecular and cellular mechanisms into one integrated hypothesis indicating that coagulopathies, including thromboses, thrombocytopenia, and other related side effects, are correlated to an interplay of the two components in the vaccine, i.e., the spike antigen and the adenoviral vector, with the innate and immune systems, which under certain circumstances can imitate the picture of a limited COVID-19 pathological picture.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/immunology , Thrombocytopenia/etiology , Thrombosis/etiology , Adenoviridae/immunology , Animals , COVID-19/immunology , COVID-19 Vaccines/immunology , Genetic Vectors/adverse effects , Genetic Vectors/immunology , Humans , Purpura, Thrombocytopenic, Idiopathic/etiology , Purpura, Thrombocytopenic, Idiopathic/immunology , Spike Glycoprotein, Coronavirus/adverse effects , Thrombocytopenia/immunology , Thrombosis/immunology , Vaccination/adverse effects
7.
Blood ; 139(10): 1564-1574, 2022 03 10.
Article in English | MEDLINE | ID: covidwho-1443789

ABSTRACT

Cases of de novo immune thrombocytopenia (ITP), including a fatality, following SARS-CoV-2 vaccination in previously healthy recipients led to studying its impact in preexisting ITP. In this study, 4 data sources were analyzed: the Vaccine Adverse Events Reporting System (VAERS) for cases of de novo ITP; a 10-center retrospective study of adults with preexisting ITP receiving SARS-CoV-2 vaccination; and surveys distributed by the Platelet Disorder Support Association (PDSA) and the United Kingdom (UK) ITP Support Association. Seventy-seven de novo ITP cases were identified in VAERS, presenting with median platelet count of 3 [1-9] ×109/L approximately 1 week postvaccination. Of 28 patients with available data, 26 responded to treatment with corticosteroids and/or intravenous immunoglobulin (IVIG), and/or platelet transfusions. Among 117 patients with preexisting ITP who received a SARS-CoV-2 vaccine, 19 experienced an ITP exacerbation (any of: ≥50% decline in platelet count, nadir platelet count <30 × 109/L with >20% decrease from baseline, and/or use of rescue therapy) following the first dose and 14 of 70 after a second dose. Splenectomized persons and those who received 5 or more prior lines of therapy were at highest risk of ITP exacerbation. Fifteen patients received and responded to rescue treatment. In surveys of both 57 PDSA and 43 UK patients with ITP, prior splenectomy was associated with worsened thrombocytopenia. ITP may worsen in preexisting ITP or be identified de novo post-SARS-CoV2 vaccination; both situations responded well to treatment. Proactive monitoring of patients with known ITP, especially those postsplenectomy and with more refractory disease, is indicated.


Subject(s)
COVID-19 Vaccines , COVID-19 , Purpura, Thrombocytopenic, Idiopathic , SARS-CoV-2 , Aged , Aged, 80 and over , Blood Platelets/immunology , Blood Platelets/metabolism , COVID-19/blood , COVID-19/epidemiology , COVID-19/immunology , COVID-19/prevention & control , COVID-19 Vaccines/administration & dosage , COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/immunology , Female , Humans , Male , Middle Aged , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Purpura, Thrombocytopenic, Idiopathic/epidemiology , Purpura, Thrombocytopenic, Idiopathic/immunology , Retrospective Studies , Risk Factors , SARS-CoV-2/immunology , SARS-CoV-2/metabolism , Splenectomy , United Kingdom/epidemiology
8.
Blood ; 138(22): 2256-2268, 2021 12 02.
Article in English | MEDLINE | ID: covidwho-1443788

ABSTRACT

SARS-CoV-2 vaccine ChAdOx1 nCoV-19 (AstraZeneca) causes a thromboembolic complication termed vaccine-induced immune thrombotic thrombocytopenia (VITT). Using biophysical techniques, mouse models, and analysis of VITT patient samples, we identified determinants of this vaccine-induced adverse reaction. Super-resolution microscopy visualized vaccine components forming antigenic complexes with platelet factor 4 (PF4) on platelet surfaces to which anti-PF4 antibodies obtained from VITT patients bound. PF4/vaccine complex formation was charge-driven and increased by addition of DNA. Proteomics identified substantial amounts of virus production-derived T-REx HEK293 proteins in the ethylenediaminetetraacetic acid (EDTA)-containing vaccine. Injected vaccine increased vascular leakage in mice, leading to systemic dissemination of vaccine components known to stimulate immune responses. Together, PF4/vaccine complex formation and the vaccine-stimulated proinflammatory milieu trigger a pronounced B-cell response that results in the formation of high-avidity anti-PF4 antibodies in VITT patients. The resulting high-titer anti-PF4 antibodies potently activated platelets in the presence of PF4 or DNA and polyphosphate polyanions. Anti-PF4 VITT patient antibodies also stimulated neutrophils to release neutrophil extracellular traps (NETs) in a platelet PF4-dependent manner. Biomarkers of procoagulant NETs were elevated in VITT patient serum, and NETs were visualized in abundance by immunohistochemistry in cerebral vein thrombi obtained from VITT patients. Together, vaccine-induced PF4/adenovirus aggregates and proinflammatory reactions stimulate pathologic anti-PF4 antibody production that drives thrombosis in VITT. The data support a 2-step mechanism underlying VITT that resembles the pathogenesis of (autoimmune) heparin-induced thrombocytopenia.


Subject(s)
Antigen-Antibody Complex/immunology , Autoantibodies/immunology , COVID-19/prevention & control , Capsid Proteins/adverse effects , Drug Contamination , Genetic Vectors/adverse effects , HEK293 Cells/immunology , Immunoglobulin G/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/etiology , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/adverse effects , Adenoviridae/immunology , Animals , Antigen-Antibody Complex/ultrastructure , Autoantibodies/biosynthesis , Capillary Leak Syndrome/etiology , Capsid Proteins/immunology , Cell Line, Transformed , /immunology , Dynamic Light Scattering , Epitopes/chemistry , Epitopes/immunology , Extracellular Traps/immunology , Extravasation of Diagnostic and Therapeutic Materials/etiology , Genetic Vectors/immunology , HEK293 Cells/chemistry , Humans , Imaging, Three-Dimensional , Immunoglobulin G/biosynthesis , Inflammation , Mice , Microscopy/methods , Platelet Activation , Proteomics , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/immunology , Sinus Thrombosis, Intracranial/diagnostic imaging , Sinus Thrombosis, Intracranial/immunology , Spike Glycoprotein, Coronavirus/immunology , Virus Cultivation
12.
J Autoimmun ; 121: 102662, 2021 07.
Article in English | MEDLINE | ID: covidwho-1385817

ABSTRACT

Herein, we consider venous immunothrombotic mechanisms in SARS-CoV-2 infection and anti-SARS-CoV-2 DNA vaccination. Primary SARS-CoV-2 infection with systemic viral RNA release (RNAaemia) contributes to innate immune coagulation cascade activation, with both pulmonary and systemic immunothrombosis - including venous territory strokes. However, anti-SARS-CoV-2 adenoviral-vectored-DNA vaccines -initially shown for the ChAdOx1 vaccine-may rarely exhibit autoimmunity with autoantibodies to Platelet Factor-4 (PF4) that is termed Vaccine-Induced Thrombotic Thrombocytopenia (VITT), an entity pathophysiologically similar to Heparin-Induced Thrombocytopenia (HIT). The PF4 autoantigen is a polyanion molecule capable of independent interactions with negatively charged bacterial cellular wall, heparin and DNA molecules, thus linking intravascular innate immunity to both bacterial cell walls and pathogen-derived DNA. Crucially, negatively charged extracellular DNA is a powerful adjuvant that can break tolerance to positively charged nuclear histone proteins in many experimental autoimmunity settings, including SLE and scleroderma. Analogous to DNA-histone interactons, positively charged PF4-DNA complexes stimulate strong interferon responses via Toll-Like Receptor (TLR) 9 engagement. A chain of events following intramuscular adenoviral-vectored-DNA vaccine inoculation including microvascular damage; microbleeding and platelet activation with PF4 release, adenovirus cargo dispersement with DNA-PF4 engagement may rarely break immune tolerance, leading to rare PF4-directed autoimmunity. The VITT cavernous sinus cerebral and intestinal venous territory immunothrombosis proclivity may pertain to venous drainage of shared microbiotal-rich areas of the nose and in intestines that initiates local endovascular venous immunity by PF4/microbiotal engagement with PF4 autoantibody driven immunothrombosis reminiscent of HIT. According to the proposed model, any adenovirus-vectored-DNA vaccine could drive autoimmune VITT in susceptible individuals and alternative mechanism based on molecular mimicry, vaccine protein contaminants, adenovirus vector proteins, EDTA buffers or immunity against the viral spike protein are secondary factors. Hence, electrochemical DNA-PF4 interactions and PF4-heparin interactions, but at different locations, represent the common denominator in HIT and VITT related autoimmune-mediated thrombosis.


Subject(s)
Autoantibodies/immunology , COVID-19/immunology , Purpura, Thrombocytopenic, Idiopathic/immunology , SARS-CoV-2/immunology , Thrombosis/immunology , Vaccines/adverse effects , COVID-19/pathology , COVID-19/prevention & control , Humans , Platelet Activation/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Purpura, Thrombocytopenic, Idiopathic/pathology , Thrombosis/chemically induced , Thrombosis/pathology , Vaccines/immunology
13.
J Stroke Cerebrovasc Dis ; 30(11): 106072, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1377775

ABSTRACT

Recently cases of vaccine-induced immune thrombotic thrombocytopenia (VITT) and thrombosis following the adenoviral vector vaccine against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) were reported. A mechanism similar to heparin-induced thrombocytopenia was proposed with antibodies to platelet factor 4 (PF4). Vaccine related arterial thrombosis in the brain is rare but life-threatening and optimal treatment is not established. We report clinical, laboratory, imaging findings and treatment in a 51-year-old female presenting with acute left middle cerebral artery (MCA) occlusion 7 days after the first dose of ChAdOx1 nCoV-19 vaccine. Due to low platelet count and suspicion of VITT she was not eligible for intravenous thrombolysis (IVT) and proceeded to mechanical thrombectomy (MER) with successful recanalization four hours after onset of symptoms. Treatment with intravenous immunoglobulin (IVIG) and heparin pentasaccharide fondaparinux was initiated. Presence of anti-PF4 antibodies was confirmed. The patient improved clinically with normalization of platelet count. Clinicians should be alert of VITT in patients with acute ischemic stroke after ChAdOx1 nCov-19 vaccination and low platelet counts. MER showed to be feasible and effective. We propose considering MER in patients with VITT and large vessel occlusion despite thrombocytopenia. High-dose IVIG should be started immediately. Alternative anticoagulation to heparin should be started 24 hours after stroke onset unless significant hemorrhagic transformation occurred. Platelet transfusion is contraindicated and should be considered only in severe hemorrhagic complications. Restenosis or reocclusion of the revascularized artery is possible due to the hypercoagulable state in VITT and angiographic surveillance after the procedure is reasonable.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Infarction, Middle Cerebral Artery/chemically induced , Ischemic Stroke/chemically induced , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Anticoagulants/therapeutic use , COVID-19/immunology , COVID-19/virology , Female , Humans , Immunoglobulins, Intravenous/therapeutic use , Infarction, Middle Cerebral Artery/diagnostic imaging , Infarction, Middle Cerebral Artery/immunology , Infarction, Middle Cerebral Artery/therapy , Ischemic Stroke/diagnostic imaging , Ischemic Stroke/immunology , Ischemic Stroke/therapy , Middle Aged , Purpura, Thrombocytopenic, Idiopathic/diagnosis , Purpura, Thrombocytopenic, Idiopathic/immunology , Purpura, Thrombocytopenic, Idiopathic/therapy , Thrombectomy , Treatment Outcome
14.
Thromb Haemost ; 121(12): 1622-1627, 2021 Dec.
Article in English | MEDLINE | ID: covidwho-1334018

ABSTRACT

BACKGROUND: Coronavirus disease 2019 vaccine ChAdOx1 nCov-19 may rarely lead to vaccine-induced thrombotic thrombocytopenia (VITT). Antibody-mediated, platelet factor 4 (PF4)-dependent platelet activation appears to resemble a key mechanism in VITT, partially comparable to heparin-induced thrombocytopenia. The use of PF4/heparin immunoassays has been proposed as part of a diagnostic approach, but their sensitivity has not been established. METHODS: Sera from 12 well-defined VITT patients were first studied by two different laboratories in functional assays. Sera where then used for an interlaboratory comparison, in which five different PF4/heparin immunoassays were used by four laboratories. RESULTS: Results for functional testing were highly concordant. VITT antibodies were also reliably detected by PF4/heparin enzyme-linked immunosorbent assays (ELISAs) (92-100%). In contrast, only 25% of VITT antibodies were reactive in a particle gel immunoassay (PaGIA), and 8% in a lateral flow assay (LFA). An automated chemiluminescence immunoassay (CLIA) was negative for all sera tested (0%). CONCLUSION: It seems feasible to establish functional antibody testing for the confirmation of VITT. For the initial screening of suspected VITT cases, PaGIA, LFA, and CLIA are useless when applied as single tests. Only ELISA-based PF4/heparin immunoassays are sensitive enough to be incorporated in the diagnostic workup. However, a combination of a positive ELISA and a negative CLIA may be useful to identify VITT antibodies in the absence of confirmatory functional assays.


Subject(s)
Antibodies/blood , Enzyme-Linked Immunosorbent Assay , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/diagnosis , Vaccination/adverse effects , Biomarkers/blood , Humans , Luminescent Measurements , Predictive Value of Tests , Purpura, Thrombocytopenic, Idiopathic/blood , Purpura, Thrombocytopenic, Idiopathic/chemically induced , Purpura, Thrombocytopenic, Idiopathic/immunology , Reproducibility of Results
15.
Blood ; 138(4): 293-298, 2021 07 29.
Article in English | MEDLINE | ID: covidwho-1331924

ABSTRACT

The development of vaccines to fight COVID-19 has been a remarkable medical achievement. However, this global immunization effort has been complicated by a rare vaccine-related outcome characterized by thrombocytopenia and thrombosis in association with platelet-activating anti-platelet factor 4 antibodies. In this Spotlight, we will discuss the recently described complication of vaccine-induced immune thrombotic thrombocytopenia (VITT) occurring in response to certain COVID-19 vaccines. Although information about this clinical condition is rapidly evolving, we will summarize our current understanding of VITT.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Purpura, Thrombocytopenic, Idiopathic/etiology , Anticoagulants/adverse effects , Anticoagulants/immunology , COVID-19/immunology , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , Disease Management , Heparin/adverse effects , Heparin/immunology , Humans , Purpura, Thrombocytopenic, Idiopathic/immunology , Purpura, Thrombocytopenic, Idiopathic/therapy , SARS-CoV-2/immunology
16.
Blood ; 138(4): 350-353, 2021 07 29.
Article in English | MEDLINE | ID: covidwho-1331923

ABSTRACT

We report 5 cases of prothrombotic immune thrombocytopenia after exposure to the ChAdOx1 vaccine (AZD1222, Vaxzevria) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients presented 5 to 11 days after first vaccination. The spectrum of clinical manifestations included cerebral venous sinus thrombosis, splanchnic vein thrombosis, arterial cerebral thromboembolism, and thrombotic microangiopathy. All patients had thrombocytopenia and markedly elevated D-dimer. Autoantibodies against platelet factor 4 (PF4) were detected in all patients, although they had never been exposed to heparin. Immunoglobulin from patient sera bound to healthy donor platelets in an AZD1222-dependent manner, suppressed by heparin. Aggregation of healthy donor platelets by patient sera was demonstrated in the presence of buffer or AZD1222 and was also suppressed by heparin. Anticoagulation alone or in combination with eculizumab or intravenous immunoglobulin (IVIG) resolved the pathology in 3 patients. Two patients had thromboembolic events despite anticoagulation at a time when platelets were increasing after IVIG. In summary, an unexpected autoimmune prothrombotic disorder is described after vaccination with AZD1222. It is characterized by thrombocytopenia and anti-PF4 antibodies binding to platelets in AZD1222-dependent manner. Initial clinical experience suggests a risk of unusual and severe thromboembolic events.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Purpura, Thrombocytopenic, Idiopathic/etiology , Thrombosis/etiology , Adult , Aged , Autoantibodies/immunology , COVID-19/immunology , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , Cohort Studies , Female , Humans , Male , Middle Aged , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/immunology , SARS-CoV-2/immunology , Thrombosis/immunology
18.
Blood ; 138(14): 1269-1277, 2021 10 07.
Article in English | MEDLINE | ID: covidwho-1317119

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a severe adverse effect of ChAdOx1 nCoV-19 COVID-19 vaccine (Vaxzevria) and Janssen Ad26.COV2.S COVID-19 vaccine, and it is associated with unusual thrombosis. VITT is caused by anti-platelet factor 4 (PF4) antibodies activating platelets through their FcγRIIa receptors. Antibodies that activate platelets through FcγRIIa receptors have also been identified in patients with COVID-19. These findings raise concern that vaccination-induced antibodies against anti-SARS-CoV-2 spike protein cause thrombosis by cross-reacting with PF4. Immunogenic epitopes of PF4 and SARS-CoV-2 spike protein were compared using in silico prediction tools and 3D modeling. The SARS-CoV-2 spike protein and PF4 share at least 1 similar epitope. Reactivity of purified anti-PF4 antibodies from patients with VITT was tested against recombinant SARS-CoV-2 spike protein. However, none of the affinity-purified anti-PF4 antibodies from 14 patients with VITT cross-reacted with SARS-CoV-2 spike protein. Sera from 222 polymerase chain reaction-confirmed patients with COVID-19 from 5 European centers were tested by PF4-heparin enzyme-linked immunosorbent assays and PF4-dependent platelet activation assays. We found anti-PF4 antibodies in sera from 19 (8.6%) of 222 patients with COVID-19. However, only 4 showed weak to moderate platelet activation in the presence of PF4, and none of those patients developed thrombotic complications. Among 10 (4.5%) of 222 patients who had COVID-19 with thrombosis, none showed PF4-dependent platelet-activating antibodies. In conclusion, antibodies against PF4 induced by vaccination do not cross-react with the SARS-CoV-2 spike protein, indicating that the intended vaccine-induced immune response against SARS-CoV-2 spike protein is not the trigger of VITT. PF4-reactive antibodies found in patients with COVID-19 in this study were not associated with thrombotic complications.


Subject(s)
Antibodies/adverse effects , COVID-19 Vaccines/adverse effects , Cross Reactions/immunology , Platelet Factor 4/immunology , Purpura, Thrombocytopenic, Idiopathic/etiology , Purpura, Thrombocytopenic, Idiopathic/immunology , Spike Glycoprotein, Coronavirus/immunology , Adult , Aged , Aged, 80 and over , Blood Platelets/immunology , COVID-19/immunology , Cohort Studies , Epitopes/immunology , Female , Heparin/metabolism , Humans , Immunoglobulin G/immunology , Male , Middle Aged , Protein Binding , Protein Domains , Purpura, Thrombocytopenic, Idiopathic/blood , Spike Glycoprotein, Coronavirus/chemistry , Young Adult
20.
Blood ; 138(4): 293-298, 2021 07 29.
Article in English | MEDLINE | ID: covidwho-1249542

ABSTRACT

The development of vaccines to fight COVID-19 has been a remarkable medical achievement. However, this global immunization effort has been complicated by a rare vaccine-related outcome characterized by thrombocytopenia and thrombosis in association with platelet-activating anti-platelet factor 4 antibodies. In this Spotlight, we will discuss the recently described complication of vaccine-induced immune thrombotic thrombocytopenia (VITT) occurring in response to certain COVID-19 vaccines. Although information about this clinical condition is rapidly evolving, we will summarize our current understanding of VITT.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Purpura, Thrombocytopenic, Idiopathic/etiology , Anticoagulants/adverse effects , Anticoagulants/immunology , COVID-19/immunology , COVID-19 Vaccines/immunology , COVID-19 Vaccines/therapeutic use , Disease Management , Heparin/adverse effects , Heparin/immunology , Humans , Purpura, Thrombocytopenic, Idiopathic/immunology , Purpura, Thrombocytopenic, Idiopathic/therapy , SARS-CoV-2/immunology
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