Novel diagnostic assays for heparin-induced thrombocytopenia.
Blood. 2013 Feb 27;
Authors: Cuker A, Rux AH, Hinds JL, Dela Cruz M, Yarovoi SV, Brown IA, Yang W, Konkle BA, Arepally GM, Watson SP, Cines DB, Sachais BS
Laboratory testing for heparin-induced thrombocytopenia (HIT) has important shortcomings. Immunoassays fail to discriminate platelet-activating from non-pathogenic antibodies. Specific functional assays are often impracticable due to the need for platelets and radioisotope. We describe two 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 PF4/heparin. DT40-luciferase (DT40-luc) is a functional test comprised of a B-cell line expressing Fc?RIIa coupled to a luciferase reporter. We compared these assays to polyspecific and IgG-specific PF4/heparin 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 14C-serotonin release assay. HIT-positive plasma demonstrated greater mean inhibition of KKO binding than HIT-negative plasma (78.9% vs. 26.0%, p<0.0001) and induced greater luciferase activity (3.14-fold basal vs. 0.96-fold basal, p<0.0001). The area under the ROC curve (AUC) was greater for KKO-I (0.93) than for the polyspecific (0.82, p=0.020) and IgG-specific ELISA (0.76, p=0.0044) and for DT40-luc (0.89) than for the IgG-specific ELISA (p=0.046). KKO-I and DT40-luc showed better discrimination than two commercially available immunoassays, are simple to perform, and hold promise for improving the specificity and feasibility of HIT laboratory testing.
PMID: 23446735 [PubMed - as supplied by publisher]