title: Novel diagnostic assays for heparin-induced thrombocytopenia.
abstract: Laboratory testing for heparin-induced thrombocytopenia (HIT) has important shortcomings. Immunoassays fail to discriminate platelet-activating from nonpathogenic antibodies. Specific functional assays are impracticable due to the need for platelets and radioisotope. We describe 2 assays that may overcome these limitations. The KKO-inhibition test (KKO-I) measures the effect of plasma on binding of the HIT-like monoclonal antibody KKO to platelet factor 4 (PF4)/heparin. DT40-luciferase (DT40-luc) is a functional test comprised of a B-cell line expressing FcγRIIa coupled to a luciferase reporter. We compared these assays to polyspecific and immunoglobulin (Ig)G-specific PF4/heparin enzyme-linked immunosorbent assays (ELISAs) in samples from 58 patients with suspected HIT and circulating anti-PF4/heparin antibodies. HIT was defined as a 4Ts score ≥ 4 and positive (14)C-serotonin release assay. HIT-positive plasma demonstrated greater mean inhibition of KKO binding than HIT-negative plasma (78.9% vs 26.0%; P < .0001) and induced greater luciferase activity (3.14-fold basal vs 0.96-fold basal; P < .0001). The area under the receiver-operating characteristic curve was greater for KKO-I (0.93) than for the polyspecific (0.82; P = .020) and IgG-specific ELISA (0.76; P = .0044) and for DT40-luc (0.89) than for the IgG-specific ELISA (P = .046). KKO-I and DT40-luc showed better discrimination than 2 commercially available immunoassays, are simple to perform, and hold promise for improving the specificity and feasibility of HIT laboratory testing.
authors: Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA. adam.cuker@uphs.upenn.edu
authors: Adam
authors: A
authors: Cuker
authors: Ann H
authors: AH
authors: Rux
authors: Jillian L
authors: JL
authors: Hinds
authors: May
authors: M
authors: Dela Cruz
authors: Serge V
authors: SV
authors: Yarovoi
authors: Isola A M
authors: IA
authors: Brown
authors: Wei
authors: W
authors: Yang
authors: Barbara A
authors: BA
authors: Konkle
authors: Gowthami M
authors: GM
authors: Arepally
authors: Stephen P
authors: SP
authors: Watson
authors: Douglas B
authors: DB
authors: Cines
authors: Bruce S
authors: BS
authors: Sachais
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000276:immunology; D002478:Cells, Cultured; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006403:Hematologic Tests; D006493:Heparin / Q000009:adverse effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013921:Thrombocytopenia / Q000139:chemically induced* / Q000175:diagnosis*
chemical_list: D000911:Antibodies, Monoclonal; D006493:Heparin