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Favaloro EJ. Laboratory testing for suspected COVID-19 vaccine-induced (immune) thrombotic thrombocytopenia. Int J Lab Hematol 2021; 43:559-570. [PMID: 34138513 PMCID: PMC8444734 DOI: 10.1111/ijlh.13629] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 05/27/2021] [Accepted: 05/28/2021] [Indexed: 12/11/2022]
Abstract
COVID‐19 (coronavirus disease 2019) represents a pandemic, and several vaccines have been produced to prevent infection and/or severe sequelae associated with SARS‐CoV‐2 (severe acute respiratory syndrome coronavirus 2) infection. There have been several reports of infrequent post vaccine associated thrombotic events, in particular for adenovirus‐based vaccines. These have variously been termed VIPIT (vaccine‐induced prothrombotic immune thrombocytopenia), VITT (vaccine‐induced [immune] thrombotic thrombocytopenia), VATT (vaccine‐associated [immune] thrombotic thrombocytopenia), and TTS (thrombosis with thrombocytopenia syndrome). In this report, the laboratory test processes, as utilised to assess suspected VITT, are reviewed. In published reports to date, there are notable similarities and divergences in testing approaches, potentially leading to identification of slightly disparate patient cohorts. The key to appropriate identification/exclusion of VITT, and potential differentiation from heparin‐induced thrombocytopenia with thrombosis (HITT), is identification of potentially differential test patterns. In summary, testing typically comprises platelet counts, D‐dimer, fibrinogen, and various immunological and functional assays for platelet factor 4 (PF4) antibodies. In suspected VITT, there is a generally highly elevated level of D‐dimer, thrombocytopenia, and PF4 antibodies can be identified by ELISA‐based assays, but not by other immunological assays typically positive in HITT. In addition, in some functional platelet activation assays, standard doses of heparin have been identified to inhibit activation in suspected VITT, but they tend to augment activation in HITT. Conversely, it is also important to not over‐diagnose VITT, given that not all cases of thrombosis post vaccination will have an immune basis and not all PF4‐ELISA positive patients will be VITT.
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Affiliation(s)
- Emmanuel J Favaloro
- Department of Haematology, Sydney Centres for Thrombosis and Haemostasis, Institute of Clinical Pathology and Medical Research (ICPMR), NSW Health Pathology, Westmead, NSW, Australia.,School of Biomedical Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia
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An Optimized and Standardized Rapid Flow Cytometry Functional Method for Heparin-Induced Thrombocytopenia. Biomedicines 2021; 9:biomedicines9030296. [PMID: 33805718 PMCID: PMC7999851 DOI: 10.3390/biomedicines9030296] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/04/2021] [Accepted: 03/10/2021] [Indexed: 11/17/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a thrombocytopenia caused by heparin and mediated by an atypical immune mechanism leading to a paradoxical high thrombotic risk, associated with severe morbidity or death. The diagnosis of HIT combines a clinical scoring of pretest probability and laboratory testing. First-line routine tests are antigen binding assays detecting specific antibodies. The most sensitive of these tests have a high HIT-negative predictive value enabling HIT diagnosis to be ruled out when negative. However, HIT-positive predictive value is low, and a functional assay evaluating the pathogenicity of the antibodies should be performed to exclude false-positive results. In contrast to screening assays, functional assays are highly specific but technically challenging, and are thus performed in referral laboratories, where platelet activation is detected using radioactive serotonin (serotonin release assay, SRA) or visually (heparin-induced platelet activation, HIPA). Flow cytometry is a possible alternative. It is, however, currently not widely used, mostly because of the lack of standardization of the published assays. This article describes and discusses the standardization of a HIT flow cytometry assay (HIT-FCA) method, which subsequently led to the development and commercialization of a CE-marked assay (HIT Confirm®, Emosis, France) as a suitable rapid HIT functional test.
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Maličev E. The use of flow cytometry in the diagnosis of heparin-induced thrombocytopenia (HIT). Transfus Med Rev 2019; 34:34-41. [PMID: 31575433 DOI: 10.1016/j.tmrv.2019.08.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 06/21/2019] [Accepted: 08/07/2019] [Indexed: 11/25/2022]
Abstract
Heparin-induced thrombocytopenia (HIT) affects some of the patients exposed to heparin. It is mediated by antibodies that recognize neoepitopes on platelet factor 4 (PF4)/heparin complexes. A HIT diagnosis requires both clinical and laboratory evaluation and remains a challenge. Since many patients develop antibodies in response to heparin, but only a few of them generate anti-PF4/heparin antibodies capable of activating platelets which consequently cause clinical complications, the performance of serologic assays is not enough to diagnose HIT. Functional assays can identify pathogenic antibodies capable of platelet activation, but they are more demanding and their limited availability contributes to the problem of diagnosing HIT. Restricted laboratories usually collect sera of multiple patients to perform functional assays only once or twice a week; hence, a HIT diagnosis can take several days. The use of flow cytometry appears to be a promising alternative in the confirmation of pathogenic anti-PF4/heparin antibodies. Flow cytometric assays detect either activation markers on a healthy donor's platelet surfaces or platelet derived microparticles formed after platelet incubation with a patient's serum. Flow cytometers are readily available in many clinical laboratories, so this technology introduces the possibility of an earlier HIT diagnosis. The objective of this review was to collect findings on flow cytometric HIT confirmations to the present date, and to review the currently available flow cytometric assays used in the diagnosis of HIT.
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Affiliation(s)
- Elvira Maličev
- Blood Transfusion Center of Slovenia, Ljubljana, Slovenia.
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Nagler M, Bakchoul T. Clinical and laboratory tests for the diagnosis of heparin-induced thrombocytopenia. Thromb Haemost 2017; 116:823-834. [DOI: 10.1160/th16-03-0240] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2016] [Accepted: 08/16/2016] [Indexed: 12/27/2022]
Abstract
SummaryA rapid diagnostic work-up is required in patients with suspected heparin-induced thrombocytopenia (HIT). However, diagnosis of HIT is challenging due to a number of practical issues and methodological limitations. Many laboratory tests and a few clinical scoring systems are available but the individual characteristics and the diagnostic accuracy of these are hard to appraise. The 4Ts score is a well evaluated clinical assessment tool with the potential to rule out HIT in many patients. Still, it requires experience and is subject to a relevant inter-observer variability. Immunoassays such as enzyme-linked immunosorbent assays or recently developed rapid assays are able to exclude HIT in a number of patients. But, accuracy of immunoassays differs depending on type of assay, threshold, antibody specificity and even manufacturer. Due to a comparatively low positive predictive value, HIT cannot be confirmed by immunoassays alone. In addition, only some of them are immediately accessible, particularly in small laboratories. While functional assays such as the serotonin release assay (SRA) and the heparin-induced platelet activation assay (HIPA) are considered as gold standard for diagnosis of HIT, they require a highly specialised laboratory. In addition, some of them are not adequately evaluated. In clinical practice, we recommend an integrated diagnostic approach combining not only clinical assessment (the 4Ts score) but immunoassays and functional assays as well. We propose a clear diagnostic algorithm supporting clinical decision-making. Furthermore, we provide an overview of all current laboratory techniques for HIT and discuss diagnostic pathways and strategies to reduce diagnostic errors, and future perspectives.
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Minet V, Dogné JM, Mullier F. Functional Assays in the Diagnosis of Heparin-Induced Thrombocytopenia: A Review. Molecules 2017; 22:molecules22040617. [PMID: 28398258 PMCID: PMC6153750 DOI: 10.3390/molecules22040617] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 04/05/2017] [Accepted: 04/08/2017] [Indexed: 01/09/2023] Open
Abstract
A rapid and accurate diagnosis in patients with suspected heparin-induced thrombocytopenia (HIT) is essential for patient management but remains challenging. Current HIT diagnosis ideally relies on a combination of clinical information, immunoassay and functional assay results. Platelet activation assays or functional assays detect HIT antibodies that are more clinically significant. Several functional assays have been developed and evaluated in the literature. They differ in the activation endpoint studied; the technique or technology used; the platelet donor selection; the platelet suspension (washed platelets, platelet rich plasma or whole blood); the patient sample (serum or plasma); and the heparin used (type and concentrations). Inconsistencies in controls performed and associated results interpretation are common. Thresholds and performances are determined differently among papers. Functional assays suffer from interlaboratory variability. This lack of standardization limits the evaluation and the accessibility of functional assays in laboratories. In the present article, we review all the current activation endpoints, techniques and methodologies of functional assays developed for HIT diagnosis.
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Affiliation(s)
- Valentine Minet
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - Jean-Michel Dogné
- Department of Pharmacy, Namur Thrombosis and Hemostasis Center (NTHC), Namur Research Institute for LIfe Sciences (NARILIS), University of Namur, Namur 5000, Belgium.
| | - François Mullier
- CHU UCL Namur, Namur Thrombosis and Hemostasis Center (NTHC), Hematology Laboratory, Université catholique de Louvain, Yvoir 5530, Belgium.
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Kerényi A, Beke Debreceni I, Oláh Z, Ilonczai P, Bereczky Z, Nagy B, Muszbek L, Kappelmayer J. Evaluation of flow cytometric HIT assays in relation to an IgG-Specific immunoassay and clinical outcome. CYTOMETRY PART B-CLINICAL CYTOMETRY 2016; 92:389-397. [PMID: 26860978 DOI: 10.1002/cyto.b.21362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Revised: 01/06/2016] [Accepted: 02/01/2016] [Indexed: 12/19/2022]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is a severe side effect of heparin treatment caused by platelet activating IgG antibodies generated against the platelet factor 4 (PF4)-heparin complex. Thrombocytopenia and thrombosis are the leading clinical symptoms of HIT. METHODS The clinical pretest probability of HIT was evaluated by the 4T score system. Laboratory testing of HIT was performed by immunological detection of antibodies against PF4-heparin complex (EIA) and two functional assays. Heparin-dependent activation of donor platelets by patient plasma was detected by flow cytometry. Increased binding of Annexin-V to platelets and elevated number of platelet-derived microparticles (PMP) were the indicators of platelet activation. RESULTS EIA for IgG isotype HIT antibodies was performed in 405 suspected HIT patients. Based on negative EIA results, HIT was excluded in 365 (90%) of cases. In 40 patients with positive EIA test result functional tests were performed. Platelet activating antibodies were detected in 17 cases by Annexin V binding. PMP count analysis provided nearly identical results. The probability of a positive flow cytometric assay result was higher in patients with elevated antibody titer. 71% of patients with positive EIA and functional assay had thrombosis. CONCLUSIONS EIA is an important first line laboratory test in the diagnosis of HIT; however, HIT must be confirmed by a functional test. Annexin V binding and PMP assays using flow cytometry are functional HIT tests convenient in a clinical diagnostic laboratory. The positive results of functional assays may predict the onset of thrombosis. © 2016 International Clinical Cytometry Society.
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Affiliation(s)
- Adrienne Kerényi
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - Ildikó Beke Debreceni
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - Zsolt Oláh
- Department of Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - Péter Ilonczai
- Department of Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - Zsuzsanna Bereczky
- Division of Clinical Laboratory Science, Faculty of Medicine, University of Debrecen, Hungary
| | - Béla Nagy
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary
| | - László Muszbek
- Division of Clinical Laboratory Science, Faculty of Medicine, University of Debrecen, Hungary
| | - János Kappelmayer
- Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary
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Diagnostic value of immunoassays for heparin-induced thrombocytopenia: a systematic review and meta-analysis. Blood 2015; 127:546-57. [PMID: 26518436 DOI: 10.1182/blood-2015-07-661215] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Accepted: 10/27/2015] [Indexed: 01/20/2023] Open
Abstract
Immunoassays are essential in the workup of patients with suspected heparin-induced thrombocytopenia. However, the diagnostic accuracy is uncertain with regard to different classes of assays, antibody specificities, thresholds, test variations, and manufacturers. We aimed to assess diagnostic accuracy measures of available immunoassays and to explore sources of heterogeneity. We performed comprehensive literature searches and applied strict inclusion criteria. Finally, 49 publications comprising 128 test evaluations in 15 199 patients were included in the analysis. Methodological quality according to the revised tool for quality assessment of diagnostic accuracy studies was moderate. Diagnostic accuracy measures were calculated with the unified model (comprising a bivariate random-effects model and a hierarchical summary receiver operating characteristics model). Important differences were observed between classes of immunoassays, type of antibody specificity, thresholds, application of confirmation step, and manufacturers. Combination of high sensitivity (>95%) and high specificity (>90%) was found in 5 tests only: polyspecific enzyme-linked immunosorbent assay (ELISA) with intermediate threshold (Genetic Testing Institute, Asserachrom), particle gel immunoassay, lateral flow immunoassay, polyspecific chemiluminescent immunoassay (CLIA) with a high threshold, and immunoglobulin G (IgG)-specific CLIA with low threshold. Borderline results (sensitivity, 99.6%; specificity, 89.9%) were observed for IgG-specific Genetic Testing Institute-ELISA with low threshold. Diagnostic accuracy appears to be inadequate in tests with high thresholds (ELISA; IgG-specific CLIA), combination of IgG specificity and intermediate thresholds (ELISA, CLIA), high-dose heparin confirmation step (ELISA), and particle immunofiltration assay. When making treatment decisions, clinicians should be a aware of diagnostic characteristics of the tests used and it is recommended they estimate posttest probabilities according to likelihood ratios as well as pretest probabilities using clinical scoring tools.
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Padmanabhan A, Jones CG, Bougie DW, Curtis BR, McFarland JG, Wang D, Aster RH. A modified PF4-dependent, CD62p expression assay selectively detects serotonin-releasing antibodies in patients suspected of HIT. Thromb Haemost 2015; 114:1322-3. [PMID: 26177881 DOI: 10.1160/th15-02-0175] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/05/2015] [Indexed: 11/05/2022]
Affiliation(s)
- Anand Padmanabhan
- Anand Padmanabhan, MD PhD, Blood Center of Wisconsin, 8733 Watertown Plank Road, Milwaukee, WI 53226-3548, USA, Tel.: +1 414 937 6045, Fax: +1 414 933 6803, E-mail:
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Groeneboer S, Lambrecht S, Dhollander A, Jacques P, Cruyssen BV, Lories RJ, Devreese K, Chiers K, Elewaut D, Verbruggen G. Optimized alkylated cyclodextrin polysulphates with reduced risks on thromboembolic accidents improve osteoarthritic chondrocyte metabolism. Rheumatology (Oxford) 2011; 50:1226-35. [PMID: 21345936 PMCID: PMC3116210 DOI: 10.1093/rheumatology/keq396] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2009] [Revised: 10/27/2010] [Indexed: 12/02/2022] Open
Abstract
OBJECTIVES To compare the ability of different cyclodextrin polysulphate (CDPS) derivatives to affect human articular cartilage cell metabolism in vitro. METHODS OA chondrocytes were cultured in alginate and exposed to 5 µg/ml of 2,3,6-tri-O-methyl-β-cyclodextrin (ME-CD), 2,3-di-O-methyl-6-sulphate-β-cyclodextrin (ME-CD-6-S), 2,6-di-O-methyl-3-sulphate-β-cyclodextrin (ME-CD-3-S), (2-carboxyethyl)-β-CDPS (CE-CDPS), (2-hydroxypropyl)-β-CDPS (HP-CDPS), 6-monoamino-6-monodeoxy-β-CDPS (MA-CDPS) or β-CDPS for 5 days. Effects on IL-1-driven chondrocyte extracellular matrix (ECM) metabolism were assayed by analysis of the accumulation of aggrecan in the interterritorial matrix, IL-6 secretion and qPCR. MA-CDPS, HP-CDPS, CE-CDPS and CDPS were analysed for their in vitro effect on coagulation and their ability to activate platelets in an in vitro assay to detect possible cross-reactivity with heparin-induced thrombocytopenia (HIT) antibodies. RESULTS The monosulphated cyclodextrins ME-CD-6-S and -3-S failed to affect aggrecan synthesis and IL-6 secretion by the OA chondrocytes. Polysulphated cyclodextrins MA-CDPS, HP-CDPS, CE-CDPS and CDPS at 5 µg/ml concentrations, on the other hand, significantly induced aggrecan production and repressed IL-6 release by the chondrocytes in culture. aPTT and PT for all derivatives were lengthened for polysaccharide concentrations >50 µg/ml. Five micrograms per millilitre of β-CDPS concentrations that significantly modulated ECM ground substance production in vitro did not affect aPTT or PT. Furthermore, CE-CDPS, in contrast to MA-CDPS, HP-CDPS and CDPS, did not significantly activate platelets, suggesting a minimal potential to induce HIT thromboembolic accidents in vivo. CONCLUSIONS CE-CDPS is a new, structurally adjusted, sulphated β-cyclodextrin derivative with preserved chondroprotective capacity and a promising safety profile.
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Affiliation(s)
- Sara Groeneboer
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Stijn Lambrecht
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Aad Dhollander
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Peggy Jacques
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Bert Vander Cruyssen
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Rik J. Lories
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Katrien Devreese
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Koen Chiers
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Dirk Elewaut
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
| | - Gust Verbruggen
- Department of Rheumatology, Laboratory of Connective Tissue Biology, Ghent University Hospital, Ghent, Department of Musculoskeletal Sciences, Division of Rheumatology, Laboratory for Skeletal Development and Joint Disorders, KU Leuven, Department of Clinical Chemistry, Microbiology and Immunology, Coagulation Laboratory, Ghent University Hospital and Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Ghent, Belgium
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Kroupis C, Theodorou M, Kounavi M, Oliveira SC, Iliopoulou E, Mavri-Vavayanni M, Melissari EN, Degiannis D. Development of a real-time PCR detection method for a FCGR2A polymorphism in the LightCycler and application in the heparin-induced thrombocytopenia syndrome. Clin Biochem 2009; 42:1685-93. [PMID: 19664613 DOI: 10.1016/j.clinbiochem.2009.07.026] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 07/14/2009] [Accepted: 07/25/2009] [Indexed: 10/20/2022]
Abstract
OBJECTIVE The FcgammaRIIa receptor is responsible for the activation of platelets by antibodies in heparin-induced thrombocytopenia (HIT). The c.497G>A polymorphism in the corresponding FCG2RA gene (H131R) has been implicated in the HIT syndrome and we aimed at its rapid and reliable determination. DESIGN AND METHODS We designed a novel asymmetric real-time PCR method in the LightCycler that uses two hybridization probes and is followed by melting curve analysis. Seventy-one post-cardiac-surgery HIT Greek patients well ascertained by clinical data, immunological and functional tests (PAT, CD62P-selectin and microparticle flow cytometric detection) were studied, along with a clinically relevant group of 49 thrombocytopenic control patients and 119 healthy subjects. RESULTS The developed method has excellent analytical characteristics (linear and efficient amplification, precision), has wide DeltaT(m) between the two alleles H and R (11.53 degrees C), and is in 100% concordance with validated controls and another commonly used screening method. The RR percentage increased from 10% in the control populations to 24% in the HIT patient group. CONCLUSION The described method is technically simple, robust, fast, and accurate. A statistically significant difference was found in the comparison between the groups of HIT patients and healthy subjects [RR vs. RH+ HH, chi(2) test, p=0.01, OR (95% C.I.) 2.81 (1.21-4.68)]. The RR frequency in the Greek population was found to be the lowest among Caucasians.
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Affiliation(s)
- Christos Kroupis
- Department of Clinical Biochemistry, Attikon University Hospital, University of Athens Medical School, 1 Rimini Street, Haidari, Greece.
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A clinical-laboratory approach contributing to a rapid and reliable diagnosis of heparin-induced thrombocytopenia. Thromb Res 2008; 123:137-45. [PMID: 18582919 DOI: 10.1016/j.thromres.2008.04.020] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Revised: 04/17/2008] [Accepted: 04/24/2008] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Heparin-induced thrombocytopenia (HIT) remains a very challenging diagnosis. The first objective of this study was to compare the performance of the ID-H/PF4 PaGIA with the Asserachrom HPIA ELISA. The main purpose was to evaluate the diagnostic utility of the combination of the H/PF4 PaGIA with the clinical "4T's" score as a screening strategy. MATERIALS AND METHODS 102 patients with clinical suspicion of HIT were classified into risk groups using the 4T's score. The presence of HIT antibodies was assessed by two immunoassays and confirmed by a functional flow cytometric assay. RESULTS Comparison of the ID-H/PF4 PaGIA with the Asserachrom HPIA ELISA demonstrated a comparable technical performance, being an excellent screening test to rule out HIT (negative predictive value or NPV=100%). According to the 4T's score, HIT was excluded in all low risk patients (NPV=100%). ELISA optical density levels were significantly different between all risk groups (P-values<0.01). In contrast, due to the low positive predictive value (22%) and weak positive likelihood ratio (2.6), a positive ID-H/PF4 PaGIA result did not considerably increase the probability of HIT. CONCLUSION Our study confirms the combination of the 4T's score with the ID-H/PF4 PaGIA as a reliable strategy to rule out HIT. Yet, confirming positive ID-H/PF4 PaGIA results by flow cytometry within 1-2 h after blood sampling remains necessary. This novel clinical-laboratory approach can contribute in a rapid and reliable way to the definite diagnosis of HIT.
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Abstract
Heparin-induced thrombocytopenia (HIT) represents an immune reaction to heparin, which if unrecognized and untreated, has the potential for catastrophic thrombotic events. The demonstration of antibodies directed against the heparin-platelet factor 4 (H-PF4) complex is an important component of the diagnosis of HIT. Typically, test results are not rapidly available, and the diagnosis therefore rests principally on clinical grounds. Nevertheless, the presence of H-PF4 antibodies provides important confirmation of the diagnosis, and may predict for adverse cardiac events even in the absence of HIT. Although more research is certainly required, the use of alternative (non-heparin) anticoagulants for cardiac surgery and other cardiovascular procedures would substantially reduce the incidence of HIT and could possibly improve patient outcomes.
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Affiliation(s)
- John L Francis
- Florida Hospital Institute of Translational Research, Orlando, FL 32804, USA.
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14
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Savi P, Chong BH, Greinacher A, Gruel Y, Kelton JG, Warkentin TE, Eichler P, Meuleman D, Petitou M, Herault JP, Cariou R, Herbert JM. Effect of fondaparinux on platelet activation in the presence of heparin-dependent antibodies: a blinded comparative multicenter study with unfractionated heparin. Blood 2004; 105:139-44. [PMID: 15388575 DOI: 10.1182/blood-2004-05-2010] [Citation(s) in RCA: 156] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Heparin-induced thrombocytopenia (HIT) is a complication of heparin therapy caused by antibodies against a complex of platelet factor 4 and heparin. Fondaparinux (Arixtra) is a new synthetic selective factor Xa inhibitor. We performed a serologic study to determine the cross-reactivity of HIT sera with fondaparinux. Using a prospective, blinded study design, 39 clinically and serologically confirmed sera from patients with HIT and 15 control sera were sent to 3 different laboratories, each of which specialized in a particular HIT assay. These include the serotonin release assay, heparin-induced platelet agglutination assay, and platelet aggregation assay. Two of 82 assays (2.4%) performed in the presence of control sera were positive, both with unfractionated heparin. In the presence of HIT sera, 75 of 94 (79.8%) evaluable assays were positive with unfractionated heparin; fondaparinux was significantly (P < .001) less reactive than unfractionated heparin, only 3 of 91 evaluable assays (3.3%) being positive. Using flow cytometry, unlike unfractionated heparin, fondaparinux did not induce the binding of PAC1 and anti-CD62 monoclonal antibodies or of annexin V to platelets with HIT sera. Together, these results suggest that fondaparinux is nonreactive to HIT sera and raise the possibility that the drug may be used for prophylaxis and treatment of thrombosis in patients with a history of HIT.
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Affiliation(s)
- Pierre Savi
- Cardiovascular/Thrombosis Research Department, Sanofi-Synthelabo Recherche, Toulouse, France.
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Papalambros E, Sigala F, Travlou A, Bastounis E, Mirilas P. P-selectin and antibodies against heparin-platelet factor 4 in patients with venous or arterial diseases after a 7-day heparin treatment1 1No competing interests declared. J Am Coll Surg 2004; 199:69-77. [PMID: 15217633 DOI: 10.1016/j.jamcollsurg.2004.02.027] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2003] [Revised: 01/21/2004] [Accepted: 02/25/2004] [Indexed: 11/23/2022]
Abstract
BACKGROUND We investigated heparin influence on P-selectin (platelet adhesion molecule), and the association of P-selectin with antibodies against heparin-platelet factor 4, known mediators of heparin induced thrombocytopenia (HIT) occurring in about 5% of vascular patients. STUDY DESIGN This cohort study included 78 patients, 22 to 90 years old (mean age +/- SD, 66.5 +/- 12.2 years), suffering from arterial thromboembolism (n = 43), deep vein thrombosis (n = 21), and peripheral arterial occlusive disease (PAOD) (n = 14). Plasma P-selectin was tested by ELISA before heparin administration (day 1), and under heparin treatment (day 7). HIT antibodies on day 7 were assayed using a sandwich-type ELISA. Platelets and fibrinogen were measured on days 1 and 7. P-selectin was also examined in 30 healthy controls, 22 to 81 years old (49.8 +/- 16.4 years). RESULTS On day 7, patients with PAOD had increased P-selectin and HIT antibodies, and decreased platelets compared with patients with arterial thromboembolism or deep vein thrombosis, in whom P-selectin decreased, and HIT antibodies were mostly negative. Fibrinogen increased in all patients. HIT antibody titers and P-selectin were positively associated and were increased in nine patients who developed lower limb artery occlusion or bypass thrombosis, stroke, or myocardial infarction during hospitalization (days 5 to 24). Five of these patients suffered from PAOD and the majority had taken heparin in the past. CONCLUSIONS P-selectin and HIT antibodies could be useful markers of HIT syndrome-associated thromboses during hospitalization of vascular patients receiving heparin. In arterial thromboembolism or deep vein thrombosis, P-selectin decreases without HIT antibody development. In PAOD, their concomitant increase may alert the surgeon to forthcoming life-threatening complications.
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Affiliation(s)
- Efstathios Papalambros
- First Department of Surgery, Laiko Hospital, University of Athens Medical School, Athens, Greece
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Gobbi G, Mirandola P, Tazzari PL, Talarico E, Caimi L, Martini G, Papa S, Conte R, Manzoli FA, Vitale M. New laboratory test in flow cytometry for the combined analysis of serologic and cellular parameters in the diagnosis of heparin-induced thrombocytopenia. ACTA ACUST UNITED AC 2004; 58:32-8. [PMID: 14994373 DOI: 10.1002/cyto.b.10062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Heparin-induced thrombocytopenia (HIT) is a major complication of heparin therapy. A quick and reliable laboratory assay for the combined determination of pathogenic anti-heparin and platelet factor 4 (H:PF4) antibodies in the serum and platelet activation is not currently available. METHODS We developed a new single-tube assay in flow cytometry that combines the detection of antibodies in the serum and their activatory properties on platelets. The assay was tested on 13 serum samples from patients with suspected HIT and six samples from normal donors. The presence of anti-H:PF4 antibody complexes was detected by H:PF4-coated beads, and donor platelet activation induced by HIT sera was determined by Annexin V binding. All data were compared with the patients' clinical setting, laboratory tests, and standard enzyme-linked immunosorbent assay detection of anti-H:PF4 antibodies. RESULTS This flow cytometry assay allowed unequivocal, simultaneous detection of anti-H:PF4 antibodies in sera and their activatory properties on platelets. All cases for which the diagnosis of HIT was confirmed were detected by the flow assay. CONCLUSIONS This assay, combining for the first time functional and nonfunctional testing on anti-H:PF4 antibodies, is likely to influence the clinical decision for the management of HIT patients.
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Affiliation(s)
- Giuliana Gobbi
- Department of Anatomy, Human Anatomy Section, University of Parma, Parma, Italy
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Kottke-Marchant K, Bontempo FA. A positive in vitro assay is required to diagnose heparin-induced thrombocytopenia. Med Clin North Am 2003; 87:1215-24. [PMID: 14680302 DOI: 10.1016/s0025-7125(03)00108-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
A 57-year-old woman is admitted for coronary artery bypass graft. She has had a recent coronary angiogram (with heparin exposure), which revealed high-grade stenoses of the left anterior descending coronary artery, right coronary artery, and left circumflex artery. The preoperative platelet count is 300,000/microL. Heparin is administered during cardiopulmonary bypass. The platelet count on postoperative day 1 is 160,000/microL and on postoperative day 6 is 60,000/microL. Heparin-induced thrombocytopenia (HIT) is suspected and HIT assays are ordered.
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Affiliation(s)
- Kandace Kottke-Marchant
- Section of Hemostasis and Thrombosis, Department of Clinical Pathology, The Cleveland Clinic Foundation, 9500 Euclid Avenue, L30, Cleveland, OH 44195, USA.
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Leo A, Winteroll S. Laboratory diagnosis of heparin-induced thrombocytopenia and monitoring of alternative anticoagulants. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2003; 10:731-40. [PMID: 12965896 PMCID: PMC193890 DOI: 10.1128/cdli.10.5.731-740.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Albrecht Leo
- Blood Bank, Institute for Immunology, University Medical Center, Heidelberg University, Heidelberg, Germany.
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Gobbi G, Mirandola P, Tazzari PL, Ricci F, Caimi L, Cacchioli A, Papa S, Conte R, Vitale M. Flow cytometry detection of serotonin content and release in resting and activated platelets. Br J Haematol 2003; 121:892-6. [PMID: 12786800 DOI: 10.1046/j.1365-2141.2003.04369.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Early detection of platelet activation is important for the diagnosis and follow-up of several pathological conditions that primarily or secondarily involve platelets in their pathogenesis. The golden standard assay to detect thrombocyte activation is represented by the release of serotonin, classically performed by demanding methodologies, such as high-performance liquid chromatography, 14C-labelling and enzyme-linked immunosorbent assay (ELISA). We developed a non-radioactive method, based on individual cells, for the detection of serotonin content in activated and resting platelets by flow cytometry. The assay was standardized on cells activated by Ca2+ ionophore or by sera from patients with heparin-induced thrombocytopenia (HIT). Cells were identified by CD41a surface staining and their serotonin content measured by specific antiserotonin intracytoplasmic staining, while their activation was independently shown by annexin V binding. Cellular degranulation was detected by flow cytometry in all the cases that were also positive by standard ELISA. Moreover, multiparametric flow cytometry analysis revealed that, although virtually all activated cells bind annexin V, serotonin was released only by the platelet subset that downmodulates surface CD41a.
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Affiliation(s)
- Giuliana Gobbi
- Department of Anatomy, Pharmacology and Forensic Medicine, Human Anatomy Section, University of Parma, Ospedale Maggiore, Via Gramsci. 14, I-43100 Parma, Italy
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