Cross-competition of KKO binding to human PF4/heparin with HIT sera by ELISA.

Binding of 41 HIT sera tested against human PF4 heparin complexes is shown in squares as well as binding by fetal bovine serum (FBS) and normal sera (NS) controls. Binding of KKO in the presence of competing FBS, NS, and HIT sera is shown as circles. The HIT samples are ordered from the least to the greatest degree of block.