Heparin induced thrombocytopenia antibodies in Covid-19.
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ABSTRACT:
SUBMITTER: Patell R
PROVIDER: S-EPMC7405086 | biostudies-literature | 2020 Jul
REPOSITORIES: biostudies-literature
Publications
Heparin induced thrombocytopenia antibodies in Covid-19.
Patell Rushad R Khan Adeel M AM Bogue Thomas T Merrill Mwanasha M Koshy Anita A Bindal Poorva P Joyce Robin R Aird William C WC Neuberg Donna D Bauer Kenneth A KA Zwicker Jeffrey I JI
American journal of hematology 20200808 10
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Project description:Heparin, a widely used anticoagulant, carries the risk of an antibody-mediated adverse drug reaction, heparin-induced thrombocytopenia (HIT). A subset of heparin-treated patients produces detectable levels of antibodies against complexes of heparin bound to circulating platelet factor 4 (PF4). Using a genome-wide association study (GWAS) approach, we aimed to identify genetic variants associated with anti-PF4/heparin antibodies that account for the variable antibody response seen in HIT. We performed a GWAS on anti-PF4/heparin antibody levels determined via polyclonal enzyme-linked immunosorbent assays. Our discovery cohort (n = 4237) and replication cohort (n = 807) constituted patients with European ancestry and clinical suspicion of HIT, with cases confirmed via functional assay. Genome-wide significance was considered at α = 5 × 10-8. No variants were significantly associated with anti-PF4/heparin antibody levels in the discovery cohort at a genome-wide significant level. Secondary GWAS analyses included the identification of variants with suggestive associations in the discovery cohort (α = 1 × 10-4). The top variant in both cohorts was rs1555175145 (discovery β = -0.112 [0.018], P = 2.50 × 10-5; replication β = -0.104 [0.051], P = .041). In gene set enrichment analysis, 3 gene sets reached false discovery rate-adjusted significance (q < 0.05) in both discovery and replication cohorts: "Leukocyte Transendothelial Migration," "Innate Immune Response," and "Lyase Activity." Our results indicate that genomic variation is not significantly associated with anti-PF4/heparin antibody levels. Given our power to identify variants with moderate frequencies and effect sizes, this evidence suggests genetic variation is not a primary driver of variable antibody response in heparin-treated patients with European ancestry.
| S-EPMC9327558 | biostudies-literature
Project description:Heparin thromboprophylaxis is routinely administered during hospitalization for COVID-19. Because of the immune stimulation related to COVID-19, there is ongoing concern regarding a heightened incidence of heparin-induced thrombocytopenia (HIT). We performed a literature search using PubMed, EMBASE, Cochrane, and medRxiv database to identify studies that reported clinical and laboratory characteristics and/or the incidence of HIT in patients with COVID-19. The primary aim was to systematically review the clinical features and outcomes of patients with COVID-19 with confirmed HIT. The secondary objective was to perform a meta-analysis to estimate the incidence of HIT in hospitalized patients with COVID-19. A meta-analysis of 7 studies including 5849 patients revealed the pooled incidence of HIT in COVID-19 of 0.8% (95% confidence interval [CI], 0.2%-3.2%; I2 = 89%). The estimated incidences were 1.2% (95% CI, 0.3%-3.9%; I2 = 65%) vs 0.1% (95% CI, 0.0%-0.4%; I2 = 0%) in therapeutic vs prophylactic heparin subgroups, respectively. The pooled incidences of HIT were higher in critically ill patients with COVID-19 (2.2%; 95% CI, 0.6%-8.3%; I2 = 72.5%) compared with noncritically ill patients (0.1%; 95% CI, 0.0%-0.4%: I2 = 0%). There were 19 cases of confirmed HIT and 1 with autoimmune HIT for clinical and laboratory characterization. The median time from heparin initiation to HIT diagnosis was 13.5 days (interquartile range, 10.75-16.25 days). Twelve (63%) developed thromboembolism after heparin therapy. In conclusion, the incidence of HIT in patients with COVID-19 was comparable to patients without COVID-19, with higher incidences with therapeutic anticoagulation and in critically ill patients.
| S-EPMC8455241 | biostudies-literature
Project description:IntroductionHeparin-induced thrombocytopenia (HIT) is a rare and serious immune-mediated complication of heparin therapy which is seldom reported in association with COVID-19. This report aims to present a case of accelerated HIT in a severe COVID-19 patient.Case reportA 63-year-old man presents with symptoms of COVID-19 for one week. He was conscious, ordinated, feverish, and had diffused chest crackles. Initial laboratory tests revealed elevated C-reactive protein of 87.66 mg/dL, elevated D-dimmer of 1258.9 ng/ml, elevated ferritin of 1020 ng/ml, and his platelet count was within the normal range. Polymerase chain reaction (PCR) confirmed the diagnosis of COVID-19. On the 9th day of admission, he developed a progressive worsening of dyspnea. His D-dimmer level significantly increased to 7020 ng/ml, and his interleukin-6 was 27.3 pg/ml. Hence, we started him on unfractionated heparin (UFH) for thromboprophylaxis. On the 12th day of hospitalization, the platelet count dropped from 258000 to 111000 cells/μL. He had a high probability of HIT (4Ts score = 6). As a result, we discontinued UFH and switched him to apixaban. His platelet count normalized (174000 cells/μL) within two weeks of ceasing UHF.DiscussionHIT results from the production of antibodies against platelet factor 4/heparin complexes. It is associated with a diminished platelet count within 5-10 days post heparin initiation. Because thrombocytopenia can occur in COVID-19 patients, HIT is seldom suspected.ConclusionHIT should be considered a differential diagnosis in COVID-19 patients with thrombocytopenia.
| S-EPMC9090824 | biostudies-literature
Project description:Heparin-induced thrombocytopenia (HIT) occurs in approximately 3% of patients receiving heparinoids. About 30-75% of patients with type 2 of HIT develop thrombosis as a result of platelet activation. The most important clinical symptom is thrombocytopenia. Patients with severe COVID-19 are among those receiving heparinoids. This meta-analysis performed to picture the current knowledge and results of published studies in this field. Three search engines were searched and 575 papers were found. After evaluation, 37 articles were finally selected of which 13 studies were quantitatively analyzed. The pooled frequency rate of suspected cases with HIT in 13 studies with 11,241 patients was 1.7%. The frequency of HIT was 8.2% in the extracorporeal membrane oxygenation subgroup with 268 patients and 0.8% in the hospitalization subgroup with 10,887 patients. The coincidence of these two conditions may increase the risk of thrombosis. Of the 37 patients with COVID-19 and confirmed HIT, 30 patients (81%) were treated in the intensive care unit or had severe COVID-19. The most commonly used anticoagulants were UFH in 22 cases (59.4%). The median platelet count before treatment was 237 (176-290) x 103/µl and the median nadir platelet count was 52 (31-90.5) x 103/µl.
| S-EPMC10203678 | biostudies-literature
Project description:Immune complexes consisting of heparin, platelet factor 4 (PF4), and PF4/heparin-reactive antibodies are central to the pathogenesis of heparin-induced thrombocytopenia (HIT). It is as yet unclear what triggers the initial induction of pathogenic antibodies. We identified B cells in peripheral blood of healthy adults that produce PF4/heparin-specific antibodies following in vitro stimulation with proinflammatory molecules containing deoxycytosine-deoxyguanosine (CpG). Similarly, B cells from unmanipulated wild-type mice produced PF4/heparin-specific antibodies following in vitro or in vivo CpG stimulation. Thus, both healthy humans and mice possess preexisting inactive/tolerant PF4/heparin-specific B cells. The findings suggest that breakdown of tolerance leads to PF4/heparin-specific B-cell activation and antibody production in patients developing HIT. Consistent with this concept, mice lacking protein kinase C? (PKC?) that are prone to breakdown of B-cell tolerance produced anti-PF4/heparin antibodies spontaneously. Therefore, breakdown of tolerance can lead to PF4/heparin-specific antibody production, and B-cell tolerance may play an important role in HIT pathogenesis.
| S-EPMC3916881 | biostudies-other
Project description:Heparin-induced thrombocytopenia (HIT) is a prothrombotic disorder mediated by complexes between platelet factor 4 (PF4) and heparin or other polyanions, but the risk of thrombosis extends beyond exposure to heparin implicating other PF4 partners. We recently reported that peri-thrombus endothelium is targeted by HIT antibodies, but the binding site(s) has not been identified. We now show that PF4 binds at multiple discrete sites along the surface of extended strings of von Willebrand factor (VWF) released from the endothelium following photochemical injury in an endothelialized microfluidic system under flow. The HIT-like monoclonal antibody KKO and HIT patient antibodies recognize PF4-VWF complexes, promoting platelet adhesion and enlargement of thrombi within the microfluidic channels. Platelet adhesion to the PF4-VWF-HIT antibody complexes is inhibited by antibodies that block FcγRIIA or the glycoprotein Ib-IX complex on platelets. Disruption of PF4-VWF-HIT antibody complexes by drugs that prevent or block VWF oligomerization attenuate thrombus formation in a murine model of HIT. Together, these studies demonstrate assembly of HIT immune complexes along VWF strings released by injured endothelium that might propagate the risk of thrombosis in HIT. Disruption of PF4-VWF complex formation may provide a new therapeutic approach to HIT.
| S-EPMC7146020 | biostudies-literature
Project description:ImportanceHeparin-induced thrombocytopenia (HIT) is a life-threatening condition that requires urgent diagnostic clarification. However, knowledge of the diagnostic utility of the recommended diagnostic tests is limited in clinical practice.ObjectiveTo evaluate the current diagnostic practice for managing the suspicion of HIT.Design, setting, and participantsThis prospective diagnostic study was conducted from January 2018 to May 2021 among consecutive patients with suspected HIT from 11 study centers in Switzerland, Germany, and the United States. Detailed clinical data and laboratory information were recorded. Platelet factor 4/heparin antibodies were quantified using an automated chemiluminescent immunoassay (CLIA). A washed-platelet heparin-induced platelet activation (HIPA) test was used as a reference standard to define HIT.ExposuresSuspicion of HIT.Main outcomes and measuresThe primary outcome was the diagnostic accuracy of the 4Ts score, the CLIA, and the recommended algorithm serially combining both tests.ResultsOf 1448 patients included between 2018 and 2021, 1318 were available for the current analysis (median [IQR] age, 67 [57-75] years; 849 [64.6%] male). HIPA was positive in 111 patients (prevalence, 8.4%). The most frequent setting was intensive care unit (487 [37.0%]) or cardiovascular surgery (434 [33.0%]). The 4Ts score was low risk in 625 patients (46.8%). By 2 × 2 table, the numbers of patients with false-negative results were 10 (9.0%; 4Ts score), 5 (4.5%; CLIA), and 15 (13.5%; recommended diagnostic algorithm). The numbers of patients with false-positive results were 592 (49.0%; 4Ts score), 73 (6.0%; CLIA), and 50 (4.1%; recommended diagnostic algorithm), respectively.Conclusions and relevanceIn this diagnostic study of patients suspected of having HIT, when the recommended diagnostic algorithm was used in clinical practice, antibody testing was required in half the patients. A substantial number of patients were, however, still misclassified, which could lead to delayed diagnosis or overtreatment. Development of improved diagnostic algorithms for HIT diagnosis should be pursued.
| S-EPMC10966416 | biostudies-literature
Project description: Not available
| S-EPMC10332759 | biostudies-literature
Project description:The risk for developing heparin-induced thrombocytopenia in healthy individuals is thought to be low, but monitoring recommendations remain controversial. Therefore, a retrospective cohort study was conducted to identify the incidence of thrombocytopenic events in a healthy research population exposed and re-exposed to continuous intravenous (IV) unfractionated heparin. The Division of Sleep Medicine and the Centre for Clinical Investigations at Brigham and Women's Hospital, Boston, Massachusetts, United States, instituted a standardized platelet monitoring procedure for all research protocols that involved heparin to detect platelet count decreases. Protocol-related frequent blood sampling required use of continuous IV unfractionated heparin infusion (5,000 unit/L in 0.45% saline at 40 mL/h) to maintain line patency over extended periods of IV access. From the years 2009 to 2012, a total of 273 healthy volunteers enrolled in Sleep Medicine research protocols met study criteria as having been exposed and/or re-exposed to continuously infused intravenous heparin for at least 4 hours. The mean continuous heparin exposure time was 88 ± 82 SD hours with a total of 397 heparin exposure and re-exposure events. Platelet count measurements were obtained on 629 occasions, representing a range from 2 to 9 draws per participant. No platelet count decrease of more than 50% was detected. There were no detected adverse bleeding or thrombotic events. In this retrospective study of healthy volunteers involved in a rigorously applied inpatient platelet monitoring protocol, heparin exposure and re-exposure did not lower platelet concentration and, therefore, does not appear to be associated with increased risk of HIT in this population.
| S-EPMC6524859 | biostudies-literature
Project description:Heparin-induced thrombocytopenia (HIT), a severe autoimmune disorder, occurs in patients undergoing heparin therapy. The presence of platelet-activating antibodies against platelet factor 4/Heparin in the blood confirms patients suffering from HIT. The most widely used methods for HIT diagnosis are immunoassays but the results only suit to rule out HIT as the assays provide only around 50% specificity. To confirm HIT, samples with positive results in immunoassays are retested in functional assays (>98% specificity) that track platelet-activating antibodies via platelet aggregation. However, the protocols in functional assays are either time-consuming (due to the requirement of the detection of serotonin release) or require highly trained staff for the visualization of platelets. Here, we applied a cheap and easy-to-use contactless sensor, which employs high-frequency microwaves to detect the changes in the resonant frequency caused by platelet aggregation/activation. Analysis of change in conductivity and permittivity allowed us to distinguish between HIT-like (KKO) and non-HIT-like (RTO) antibodies. KKO caused a stronger reduction of conductivity of platelet samples than RTO. Our results imply that the high-frequency contactless sensor can be a promising approach for the development of a better and easier method for the detection of HIT.
| S-EPMC9694871 | biostudies-literature