Novel diagnostic assays for heparin-induced thrombocytopenia

Adam Cuker, Ann H. Rux, Jillian L. Hinds, May Dela Cruz, Serge V. Yarovoi, Isola A. M. Brown, Wei Yang, Barbara A. Konkle, Gowthami M. Arepally, Stephen P. Watson, Douglas B. Cines and Bruce S. Sachais

Key points

  • The KKO-inhibition ELISA and DT40-luciferase test are novel laboratory assays for heparin-induced thrombocytopenia

  • They showed better discrimination than 2 commercial immunoassays and may improve the specificity and feasibility of HIT laboratory testing


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 FcγRIIa 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.

  • Submitted January 18, 2013.
  • Accepted February 23, 2013.