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1.
Crit Care Med ; 50(1): e80-e86, 2022 01 01.
Article in English | MEDLINE | ID: covidwho-1574590

ABSTRACT

OBJECTIVES: Vaccine-induced immune thrombotic thrombocytopenia is an unexpected consequence of the coronavirus disease 2019 pandemic era. We reviewed the pathogenesis, clinical presentation, diagnosis, and treatment of this rare side effect. DATA SOURCES: Online search of published medical literature through PubMed, Scopus, Web of Science, and Google Scholar using the terms "COVID-19," "vaccine," "thrombosis" was performed. STUDY SELECTION: Articles were chosen for inclusion based on their relevance to coronavirus disease 2019, vaccine, and thrombosis. DATA SYNTHESIS: Vaccine-induced immune thrombotic thrombocytopenia manifests most often as unusual thromboses (cerebral venous sinus thrombosis, splanchnic vein thrombosis) but sometimes also "usual" thromboses (arterial stroke, pulmonary embolism, deep-vein thrombosis), with oftentimes severe thrombocytopenia, that becomes clinically evident 5-30 days after adenovirus-vectored coronavirus disease 2019 vaccine administration. Most patients have disseminated intravascular coagulation. These features are the result of vaccine-triggered formation of anti-platelet factor 4 immunoglobulin G that activate platelets, clinically mimicking autoimmune heparin-induced thrombocytopenia. Early recognition based on thrombosis (sometimes, hemorrhage), thrombocytopenia, and d-dimer elevation within the day 5-30 postvaccine "window" is important given treatment with high-dose IV immunoglobulin plus nonheparin anticoagulation. CONCLUSIONS: Vaccine-induced immune thrombotic thrombocytopenia is a serious complication of vaccination that is not feasible to anticipate or prevent. When the patient presents with sustained headache, neurologic symptoms/signs, abdominal pain, dyspnea, or limb pain/swelling beginning 5-30 days post vaccination, platelet count and d-dimer must be measured, and imaging for thrombosis performed. Confirmation of vaccine-induced immune thrombotic thrombocytopenia diagnosis should be ordered (platelet factor 4/polyanion enzyme-linked immunosorbent assay; platelet factor 4-enhanced platelet activation testing) as treatment is initiated (nonheparin anticoagulation, IV immunoglobulin).


Subject(s)
COVID-19 Vaccines/adverse effects , Thrombocytopenia/chemically induced , Thrombosis/chemically induced , Age Factors , COVID-19/prevention & control , COVID-19 Vaccines/administration & dosage , Enzyme-Linked Immunosorbent Assay , Humans , SARS-CoV-2 , Sex Factors , Thrombocytopenia/immunology , Thrombosis/immunology
2.
Cells ; 10(10)2021 10 18.
Article in English | MEDLINE | ID: covidwho-1477931

ABSTRACT

Several recent reports have highlighted the onset of vaccine-induced thrombotic thrombocytopaenia (VITT) in some recipients (approximately 1 case out of 100k exposures) of the ChAdOx1 nCoV-19 vaccine (AstraZeneca). Although the underlying events leading to this blood-clotting phenomenon has yet to be elucidated, several critical observations present a compelling potential mechanism. Thrombus formation requires the von Willebrand (VWF) protein to be in ultra-large multimeric state. The conservation of this state is controlled by the ADAMTS13 enzyme, whose proteolytic activity reduces the size of VWF multimers, keeping blood clotting at bay. However, ADAMTS13 cannot act on VWF that is bound to platelet factor 4 (PF4). As such, it is of particular interest to note that a common feature between subjects presenting with VITT is high titres of antibodies against PF4. This raises the possibility that these antibodies preserve the stability of ultra-large VWF complexes, leading to the formation of endothelium-anchored VWF strings, which are capable of recruiting circulating platelets and causing uncontrolled thrombosis in terminal capillaries. Here, we share our viewpoint about the current understanding of the VITT pathogenesis involving the prevention of ADAMTS13's activity on VWF by PF4 antibody-mediated stabilisation/ protection of the PF4-VWF complex.


Subject(s)
ADAMTS13 Protein/metabolism , COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Thrombocytopenia/immunology , Antibodies , Autoantibodies/immunology , Blood Platelets/metabolism , Crystallography, X-Ray , Endothelial Cells/immunology , Humans , Platelet Factor 4/metabolism , Polymorphism, Genetic , Protein Domains , Thrombocytopenia/etiology , Thrombosis/etiology , von Willebrand Factor/metabolism
3.
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
5.
Clin Appl Thromb Hemost ; 27: 10760296211040110, 2021.
Article in English | MEDLINE | ID: covidwho-1430348

ABSTRACT

Since the outbreak of Covid-19 in December, 2019, scientists worldwide have been committed to developing COVID-19 vaccines. Only when most people have immunity to SARS-CoV-2, COVID-19 can reduce even wholly overcome. So far, nine kinds of COVID-19 vaccines have passed the phase III clinical trials and have approved for use. At the same time, adverse reactions after COVID-19 vaccination have also reported. This paper focuses on the adverse effects of thrombosis and thrombocytopenia caused by the COVID-19 vaccine, especially the adenovirus-vector vaccine from AstraZeneca and Pfizer, and discusses its mechanism and possible countermeasures.


Subject(s)
Adenoviridae/genetics , COVID-19 Vaccines/adverse effects , Genetic Vectors , Thrombocytopenia/chemically induced , Thrombosis/chemically induced , Vaccination/adverse effects , Antibodies/blood , COVID-19 Vaccines/genetics , COVID-19 Vaccines/immunology , Humans , Platelet Factor 4/immunology , Risk Assessment , Risk Factors , Thrombocytopenia/blood , Thrombocytopenia/immunology , Thrombosis/blood , Thrombosis/immunology
7.
J Leukoc Biol ; 111(3): 725-734, 2022 03.
Article in English | MEDLINE | ID: covidwho-1380391

ABSTRACT

Following on from the devastating spread of COVID-19, a major global priority has been the production, procurement, and distribution of effective vaccines to ensure that the global pandemic reaches an end. However, concerns were raised about worrying side effects, particularly the occurrence of thrombosis and thrombocytopenia after administration of the Oxford/AstraZeneca and Johnson & Johnson's Janssen COVID-19 vaccine, in a phenomenon being termed vaccine-induced thrombotic thrombocytopenia (VITT). Similar to heparin-induced thrombocytopenia (HIT), this condition has been associated with the development of anti-platelet factor 4 antibodies, purportedly leading to neutrophil-platelet aggregate formation. Although thrombosis has also been a common association with COVID-19, the precise molecular mechanisms governing its occurrence are yet to be established. Recently, increasing evidence highlights the NLRP3 (NOD-like, leucine-rich repeat domains, and pyrin domain-containing protein) inflammasome complex along with IL-1ß and effete neutrophils producing neutrophil extracellular traps (NETs) through NETosis. Herein, we propose and discuss that perhaps the incidence of VITT may be due to inflammatory reactions mediated via IL-1ß/NLRP3 inflammasome activation and consequent overproduction of NETs, where similar autoimmune mechanisms are observed in HIT. We also discuss avenues by which such modalities could be treated to prevent the occurrence of adverse events and ensure vaccine rollouts remain safe and on target to end the current pandemic.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Extracellular Traps/immunology , Thrombocytopenia/etiology , Animals , COVID-19/immunology , COVID-19 Vaccines/therapeutic use , Humans , Inflammasomes/immunology , Interleukin-1beta/immunology , NLR Family, Pyrin Domain-Containing 3 Protein/immunology , Thrombocytopenia/immunology , Thrombocytopenia/prevention & control , Thrombocytopenia/therapy
9.
Nature ; 596(7873): 565-569, 2021 08.
Article in English | MEDLINE | ID: covidwho-1356565

ABSTRACT

Vaccine-induced immune thrombotic thrombocytopaenia (VITT) is a rare adverse effect of COVID-19 adenoviral vector vaccines1-3. VITT resembles heparin-induced thrombocytopaenia (HIT) in that it is associated with platelet-activating antibodies against platelet factor 4 (PF4)4; however, patients with VITT develop thrombocytopaenia and thrombosis without exposure to heparin. Here we sought to determine the binding site on PF4 of antibodies from patients with VITT. Using alanine-scanning mutagenesis5, we found that the binding of anti-PF4 antibodies from patients with VITT (n = 5) was restricted to eight surface amino acids on PF4, all of which were located within the heparin-binding site, and that the binding was inhibited by heparin. By contrast, antibodies from patients with HIT (n = 10) bound to amino acids that corresponded to two different sites on PF4. Biolayer interferometry experiments also revealed that VITT anti-PF4 antibodies had a stronger binding response to PF4 and PF4-heparin complexes than did HIT anti-PF4 antibodies, albeit with similar dissociation rates. Our data indicate that VITT antibodies can mimic the effect of heparin by binding to a similar site on PF4; this allows PF4 tetramers to cluster and form immune complexes, which in turn causes Fcγ receptor IIa (FcγRIIa; also known as CD32a)-dependent platelet activation. These results provide an explanation for VITT-antibody-induced platelet activation that could contribute to thrombosis.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19 Vaccines/immunology , Epitopes, B-Lymphocyte/immunology , Thrombocytopenia/chemically induced , Thrombocytopenia/immunology , Thrombosis/chemically induced , Thrombosis/immunology , Adult , Aged , Amino Acid Sequence , Antibodies/immunology , Binding Sites, Antibody , Female , Heparin/chemistry , Heparin/immunology , Heparin/metabolism , Humans , Kinetics , Male , Middle Aged , Models, Molecular , Platelet Activation , Platelet Factor 4/immunology , Receptors, IgG/immunology
11.
Clin Lymphoma Myeloma Leuk ; 21(10): e810-e816, 2021 10.
Article in English | MEDLINE | ID: covidwho-1313014

ABSTRACT

BACKGROUND: We previously reported elsewhere of a follicular lymphoma patient suffering from persistent COVID-19 pneumonia that was still ongoing at 2 months after onset. MATERIALS AND METHODS: We provide a follow-up report of the case along with a literature review of immunocompromised lymphoma patients experiencing prolonged COVID-19 infections. RESULTS: Although requiring a full 1 year, the presented case eventually achieved spontaneous resolution of COVID-19 pneumonia. Anti-SARS-CoV-2 antibodies could not be detected throughout the disease course, but COVID-19-directed T-cell response was found to be intact. The patient also developed secondary immune thrombocytopenia subsequent to COVID-19 pneumonia. We found 19 case reports of immunocompromised lymphoma patients with prolonged COVID-19 infections in the literature. All 5 patients who died did not receive convalescent plasma therapy, whereas resolution of COVID-19 infection was achieved in 8 out of 9 patients who received convalescent plasma therapy. CONCLUSIONS: We demonstrate through the presented case that while time-consuming, resolution of COVID-19 infections may be achieved without aid from humoral immunity if cellular immunity is intact. Immunocompromised lymphoma patients are at risk of a prolonged disease course of COVID-19, and convalescent plasma therapy may be a promising approach in such patients.


Subject(s)
COVID-19/immunology , Lymphoma, Follicular/drug therapy , Pneumonia/immunology , Rituximab/therapeutic use , SARS-CoV-2/immunology , Thrombocytopenia/immunology , Antineoplastic Agents, Immunological/therapeutic use , COVID-19/virology , Female , Follow-Up Studies , Humans , Immunocompromised Host/immunology , Lymphoma, Follicular/complications , Lymphoma, Follicular/immunology , Maintenance Chemotherapy/methods , Middle Aged , Pneumonia/complications , Pneumonia/virology , Remission, Spontaneous , SARS-CoV-2/physiology , T-Lymphocytes/immunology , T-Lymphocytes/virology , Thrombocytopenia/complications
12.
Biomolecules ; 11(7)2021 07 13.
Article in English | MEDLINE | ID: covidwho-1308294

ABSTRACT

Two adenovirus-based vaccines, ChAdOx1 nCoV-19 and Ad26.COV2.S, and two mRNA-based vaccines, BNT162b2 and mRNA.1273, have been approved by the European Medicines Agency (EMA), and are invaluable in preventing and reducing the incidence of coronavirus disease-2019 (COVID-19). Recent reports have pointed to thrombosis with associated thrombocytopenia as an adverse effect occurring at a low frequency in some individuals after vaccination. The causes of such events may be related to SARS-CoV-2 spike protein interactions with different C-type lectin receptors, heparan sulfate proteoglycans (HSPGs) and the CD147 receptor, or to different soluble splice variants of the spike protein, adenovirus vector interactions with the CD46 receptor or platelet factor 4 antibodies. Similar findings have been reported for several viral diseases after vaccine administration. In addition, immunological mechanisms elicited by viral vectors related to cellular delivery could play a relevant role in individuals with certain genetic backgrounds. Although rare, the potential COVID-19 vaccine-induced immune thrombotic thrombocytopenia (VITT) requires immediate validation, especially in risk groups, such as the elderly, chronic smokers, and individuals with pre-existing incidences of thrombocytopenia; and if necessary, a reformulation of existing vaccines.


Subject(s)
COVID-19 Vaccines/adverse effects , COVID-19/prevention & control , Thrombosis/etiology , COVID-19/immunology , Humans , Risk Factors , SARS-CoV-2/immunology , Smokers , Spike Glycoprotein, Coronavirus/immunology , Thrombocytopenia/etiology , Thrombocytopenia/immunology , Thrombosis/immunology , Vaccination/adverse effects
13.
Int J Lab Hematol ; 43(4): 547-558, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1231132

ABSTRACT

COVID-19 (coronavirus disease 2019) represents a prothrombotic disorder, and there have been several reports of platelet factor 4/heparin antibodies being present in COVID-19-infected patients. This has thus been identified in some publications as representing a high incidence of heparin-induced thrombocytopenia (HIT), whereas in others, findings have been tempered by general lack of functional reactivity using confirmation assays of serotonin release assay (SRA) or heparin-induced platelet aggregation (HIPA). Moreover, in at least two publications, data are provided suggesting that antibodies can arise in heparin naïve patients or that platelet activation may not be heparin-dependent. From this literature, we would conclude that platelet factor 4/heparin antibodies can be observed in COVID-19-infected patients, and they may occur at higher incidence than in historical non-COVID-19-infected cohorts. However, the situation is complex, since not all platelet factor 4/heparin antibodies may lead to platelet activation, and not all identified antibodies are heparin-dependent, such that they do not necessarily reflect "true" HIT. Most recently, a "HIT-like" syndrome has reported in patients who have been vaccinated against COVID-19. Accordingly, much more is yet to be learnt about the insidious disease that COVID-19 represents, including autoimmune outcomes in affected patients.


Subject(s)
Antibodies/immunology , Anticoagulants/adverse effects , COVID-19/complications , Heparin/adverse effects , Platelet Factor 4/immunology , Thrombocytopenia/chemically induced , Thrombocytopenia/complications , Animals , Anticoagulants/immunology , COVID-19/immunology , Heparin/immunology , Humans , Platelet Activation/drug effects , SARS-CoV-2/immunology , Thrombocytopenia/immunology
14.
J Med Virol ; 93(9): 5474-5480, 2021 Sep.
Article in English | MEDLINE | ID: covidwho-1219314

ABSTRACT

In this study, laboratorial parameters of hospitalized novel coronavirus (COVID-19) patients, who were complicated with severe pneumonia, were compared with the findings of cytokine storm developing in macrophage activation syndrome (MAS)/secondary hemophagocytic lymphohistiocytosis (sHLH). Severe pneumonia occurred as a result of cytokine storm in some patients who needed intensive care unit (ICU), and it is aimed to determine the precursive parameters in this situation. Also in this study, the aim is to identify laboratory criteria that predict worsening disease and ICU intensification, as well as the development of cytokine storm. This article comprises a retrospective cohort study of patients admitted to a single institution with COVID-19 pneumonia. This study includes 150 confirmed COVID-19 patients with severe pneumonia. When they were considered as severe pneumonia patients, the clinic and laboratory parameters of this group are compared with H-score criteria. Patients are divided into two subgroups; patients with worsened symptoms who were transferred into tertiary ICU, and patients with stable symptoms followed in the clinic. For the patients with confirmed COVID-19 infection, after they become complicated with severe pneumonia, lymphocytopenia (55.3%), anemia (12.0%), thrombocytopenia (19.3%), hyperferritinemia (72.5%), hyperfibrinogenemia (63.7%) and elevated lactate dehydrogenase (LDH) (90.8%), aspartate aminotransaminase (AST) (31.3%), alanine aminotransaminase (ALT) (20.7%) are detected. There were no significant changes in other parameters. Blood parameters between the pre-ICU period and the ICU period (in which their situation had been worsened and acute respiratory distress syndrome [ARDS] was developed) were also compared. In the latter group lymphocyte levels were found significantly reduced (p = 0.01), and LDH, highly sensitive troponin (hs-troponin), procalcitonin, and triglyceride levels were significantly increased (p < 0.05). In addition, there was no change in hemoglobin, leukocyte, platelet, ferritin, and liver function test levels, including patients who developed ARDS, similar to the cytokine storm developed in MAS/sHLH. COVID-19 pneumonia has similar findings as hyperinflammatory syndromes but does not seem to have typical features as in cytokine storm developed in MAS/sHLH. In the severe patient group who has started to develop ARDS signs, a decrease in lymphocyte level in addition to the elevated LDH, hs-troponin, procalcitonin, and triglyceride levels can be a predictor in progression to ICU admission and could help in the planning of anti-cytokine therapy.


Subject(s)
COVID-19/pathology , Cytokine Release Syndrome/pathology , Lymphohistiocytosis, Hemophagocytic/pathology , Macrophage Activation Syndrome/pathology , SARS-CoV-2/pathogenicity , Aged , Alanine Transaminase/blood , Anemia/blood , Anemia/diagnosis , Anemia/immunology , Anemia/pathology , Aspartate Aminotransferases/blood , Biomarkers/blood , COVID-19/blood , COVID-19/diagnosis , COVID-19/immunology , Cytokine Release Syndrome/blood , Cytokine Release Syndrome/diagnosis , Cytokine Release Syndrome/immunology , Diagnosis, Differential , Disease Progression , Female , Fibrinogen/metabolism , Humans , Hyperferritinemia/blood , Hyperferritinemia/diagnosis , Hyperferritinemia/immunology , Hyperferritinemia/pathology , Intensive Care Units , L-Lactate Dehydrogenase/blood , Lymphohistiocytosis, Hemophagocytic/blood , Lymphohistiocytosis, Hemophagocytic/diagnosis , Lymphohistiocytosis, Hemophagocytic/immunology , Lymphopenia/blood , Lymphopenia/diagnosis , Lymphopenia/immunology , Lymphopenia/pathology , Macrophage Activation Syndrome/blood , Macrophage Activation Syndrome/diagnosis , Macrophage Activation Syndrome/immunology , Male , Middle Aged , Procalcitonin/blood , Retrospective Studies , Thrombocytopenia/blood , Thrombocytopenia/diagnosis , Thrombocytopenia/immunology , Thrombocytopenia/pathology , Triglycerides/blood , Troponin/blood
15.
Arch Virol ; 166(8): 2109-2117, 2021 Aug.
Article in English | MEDLINE | ID: covidwho-1216221

ABSTRACT

Millions of people across the globe have been affected by coronavirus disease 2019 (COVID-19), which began in Wuhan, China, and is caused by SARS-CoV-2. COVID-19 has a variety of clinical characteristics and triggers immune responses required for the elimination of the viral agent. Currently, no effective treatment options are available for targeting SARS-CoV-2 infection. Repurposing of drugs such as chloroquine, thalidomide, and leflunomide alongside convalescent plasma is being employed as a therapeutic strategy. Clinical studies have shown that both asymptomatic and symptomatic patients can have an extremely active immune response that is largely attributable to immune system modulations. This includes cytokine storm syndrome (CSS), which affects the adaptive immune system, leading to exhaustion of natural killer (NK) cells and thrombocytopenia in some cases. This review examines the interaction of SARS-CoV-2 with the host immune system and the potential for the development of appropriate immunotherapy for the treatment of COVID-19.


Subject(s)
COVID-19/immunology , SARS-CoV-2/physiology , CD8-Positive T-Lymphocytes/immunology , COVID-19/therapy , Cytokine Release Syndrome/immunology , Endoplasmic Reticulum Stress/immunology , Humans , Immunotherapy , Inflammation , Killer Cells, Natural/immunology , Thrombocytopenia/immunology
16.
N Engl J Med ; 384(23): 2202-2211, 2021 06 10.
Article in English | MEDLINE | ID: covidwho-1189334

ABSTRACT

BACKGROUND: The mainstay of control of the coronavirus disease 2019 (Covid-19) pandemic is vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Within a year, several vaccines have been developed and millions of doses delivered. Reporting of adverse events is a critical postmarketing activity. METHODS: We report findings in 23 patients who presented with thrombosis and thrombocytopenia 6 to 24 days after receiving the first dose of the ChAdOx1 nCoV-19 vaccine (AstraZeneca). On the basis of their clinical and laboratory features, we identify a novel underlying mechanism and address the therapeutic implications. RESULTS: In the absence of previous prothrombotic medical conditions, 22 patients presented with acute thrombocytopenia and thrombosis, primarily cerebral venous thrombosis, and 1 patient presented with isolated thrombocytopenia and a hemorrhagic phenotype. All the patients had low or normal fibrinogen levels and elevated d-dimer levels at presentation. No evidence of thrombophilia or causative precipitants was identified. Testing for antibodies to platelet factor 4 (PF4) was positive in 22 patients (with 1 equivocal result) and negative in 1 patient. On the basis of the pathophysiological features observed in these patients, we recommend that treatment with platelet transfusions be avoided because of the risk of progression in thrombotic symptoms and that the administration of a nonheparin anticoagulant agent and intravenous immune globulin be considered for the first occurrence of these symptoms. CONCLUSIONS: Vaccination against SARS-CoV-2 remains critical for control of the Covid-19 pandemic. A pathogenic PF4-dependent syndrome, unrelated to the use of heparin therapy, can occur after the administration of the ChAdOx1 nCoV-19 vaccine. Rapid identification of this rare syndrome is important because of the therapeutic implications.


Subject(s)
Autoantibodies/blood , COVID-19 Vaccines/immunology , Platelet Factor 4/immunology , Thrombocytopenia/immunology , Thrombosis/immunology , Adult , Aged , Algorithms , Antibodies, Viral/blood , Anticoagulants/adverse effects , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Female , Flow Cytometry , Heparin/adverse effects , Humans , Male , Middle Aged , Thrombocytopenia/etiology , Thrombosis/etiology
18.
N Engl J Med ; 384(22): 2092-2101, 2021 06 03.
Article in English | MEDLINE | ID: covidwho-1174739

ABSTRACT

BACKGROUND: Several cases of unusual thrombotic events and thrombocytopenia have developed after vaccination with the recombinant adenoviral vector encoding the spike protein antigen of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (ChAdOx1 nCov-19, AstraZeneca). More data were needed on the pathogenesis of this unusual clotting disorder. METHODS: We assessed the clinical and laboratory features of 11 patients in Germany and Austria in whom thrombosis or thrombocytopenia had developed after vaccination with ChAdOx1 nCov-19. We used a standard enzyme-linked immunosorbent assay to detect platelet factor 4 (PF4)-heparin antibodies and a modified (PF4-enhanced) platelet-activation test to detect platelet-activating antibodies under various reaction conditions. Included in this testing were samples from patients who had blood samples referred for investigation of vaccine-associated thrombotic events, with 28 testing positive on a screening PF4-heparin immunoassay. RESULTS: Of the 11 original patients, 9 were women, with a median age of 36 years (range, 22 to 49). Beginning 5 to 16 days after vaccination, the patients presented with one or more thrombotic events, with the exception of 1 patient, who presented with fatal intracranial hemorrhage. Of the patients with one or more thrombotic events, 9 had cerebral venous thrombosis, 3 had splanchnic-vein thrombosis, 3 had pulmonary embolism, and 4 had other thromboses; of these patients, 6 died. Five patients had disseminated intravascular coagulation. None of the patients had received heparin before symptom onset. All 28 patients who tested positive for antibodies against PF4-heparin tested positive on the platelet-activation assay in the presence of PF4 independent of heparin. Platelet activation was inhibited by high levels of heparin, Fc receptor-blocking monoclonal antibody, and immune globulin (10 mg per milliliter). Additional studies with PF4 or PF4-heparin affinity purified antibodies in 2 patients confirmed PF4-dependent platelet activation. CONCLUSIONS: Vaccination with ChAdOx1 nCov-19 can result in the rare development of immune thrombotic thrombocytopenia mediated by platelet-activating antibodies against PF4, which clinically mimics autoimmune heparin-induced thrombocytopenia. (Funded by the German Research Foundation.).


Subject(s)
Autoantibodies/blood , COVID-19 Vaccines/adverse effects , Platelet Factor 4/immunology , Thrombocytopenia/etiology , Thrombosis/etiology , Adult , Autoimmune Diseases/etiology , Blood Chemical Analysis , Disseminated Intravascular Coagulation/etiology , Enzyme-Linked Immunosorbent Assay , Fatal Outcome , Female , Humans , Intracranial Hemorrhages/etiology , Male , Middle Aged , Platelet Activation , Thrombocytopenia/immunology , Thrombosis/immunology , Young Adult
19.
Int J Lab Hematol ; 43(5): 895-906, 2021 Oct.
Article in English | MEDLINE | ID: covidwho-1145304

ABSTRACT

Although platelets are traditionally recognized for their central role in hemostasis, the presence of chemotactic factors, chemokines, adhesion molecules, and costimulatory molecules in their granules and membranes indicates that they may play an immunomodulatory role in the immune response, flanking their capacity to trigger blood coagulation and inflammation. Indeed, platelets play a role not only in the innate immune response, through the expression of Toll-like receptors (TLRs) and release of inflammatory cytokines, but also in the adaptive immune response, through expression of key costimulatory molecules and major histocompatibility complex (MHC) molecules capable to activate T cells. Moreover, platelets release huge amounts of extracellular vesicles capable to interact with multiple immune players. The function of platelets thus extends beyond aggregation and implies a multifaceted interplay between hemostasis, inflammation, and the immune response, leading to the amplification of the body's defense processes on one hand, but also potentially degenerating into life-threatening pathological processes on the other. This narrative review summarizes the current knowledge and the most recent updates on platelet immune functions and interactions with infectious agents, with a particular focus on their involvement in COVID-19, whose pathogenesis involves a dysregulation of hemostatic and immune processes in which platelets may be determinant causative agents.


Subject(s)
Blood Platelets/pathology , COVID-19/pathology , Inflammation/pathology , Thrombosis/pathology , Animals , Blood Platelets/immunology , COVID-19/blood , COVID-19/complications , COVID-19/immunology , Extracellular Vesicles/immunology , Extracellular Vesicles/pathology , Hemostasis , Humans , Immunity, Innate , Inflammation/blood , Inflammation/etiology , Inflammation/immunology , Platelet Activation , SARS-CoV-2/immunology , Thrombocytopenia/blood , Thrombocytopenia/etiology , Thrombocytopenia/immunology , Thrombocytopenia/pathology , Thrombosis/blood , Thrombosis/etiology , Thrombosis/immunology
20.
Br J Haematol ; 192(6): 973-977, 2021 03.
Article in English | MEDLINE | ID: covidwho-751791

ABSTRACT

Thrombocytopenia has been identified as a common complication of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in the general population. In an attempt to determine the impact of coronavirus disease 2019 (COVID-19) in patients with immune thrombocytopenia (ITP), a retrospective single-centre study was performed. Thrombocytosis was observed in patients with chronic ITP after SARS-CoV-2 infection, frequently needing treatment adjustment or even discontinuation of therapy. Relapses and newly diagnosed cases showed a fast response after initial treatment compared to ITP. Reduced immune activity due to lymphopenia during COVID-19 could explain this paradoxical effect, although further studies are needed.


Subject(s)
COVID-19/blood , Thrombocytopenia/virology , Adult , Aged , Aged, 80 and over , COVID-19/pathology , COVID-19/virology , Female , Humans , Male , Middle Aged , Retrospective Studies , SARS-CoV-2/isolation & purification , Thrombocytopenia/blood , Thrombocytopenia/immunology , Thrombocytopenia/pathology
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