title: Evaluation of flow cytometric HIT assays in relation to an IgG-Specific immunoassay and clinical outcome.
abstract: 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.
  
  
  
  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.
  
  
  
  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.
  
  
  
  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.
authors: Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: Adrienne
authors: A
authors: Kerényi
authors: Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: Ildikó
authors: I
authors: Beke Debreceni
authors: Department of Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: Zsolt
authors: Z
authors: Oláh
authors: Department of Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: Péter
authors: P
authors: Ilonczai
authors: Division of Clinical Laboratory Science, Faculty of Medicine, University of Debrecen, Hungary.
authors: Zsuzsanna
authors: Z
authors: Bereczky
authors: Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: Béla
authors: B
authors: Nagy
authors: Division of Clinical Laboratory Science, Faculty of Medicine, University of Debrecen, Hungary.
authors: László
authors: L
authors: Muszbek
authors: Department of Laboratory Medicine, Faculty of Medicine, University of Debrecen, Hungary.
authors: János
authors: J
authors: Kappelmayer
mesh_terms: D001792:Blood Platelets / Q000378:metabolism; D055252:Cell-Derived Microparticles / Q000378:metabolism*; D005260:Female; D005434:Flow Cytometry / Q000379:methods; D006493:Heparin / Q000097:blood; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008297:Male; D015539:Platelet Activation; D013921:Thrombocytopenia / Q000097:blood / Q000175:diagnosis* / Q000276:immunology / Q000628:therapy
chemical_list: D006493:Heparin
keywords: 4T score; flow cytometry; heparin-induced thrombocytopenia; platelet microparticles; thrombosis