Binding of KKO and RTO to PF4: effect of heparin.

(A) Binding of KKO to microtiter wells coated with hPF4 (•) or hPF4/heparin (▪) expressed as absorbance at 405 nm. (B) Binding of RTO to wells coated with hPF4 (○) or hPF4/heparin (□). (C) Heparin dependence of KKO was measured by ELISA using wells coated with a fixed concentration of hPF4 and varying concentrations of heparin. The data shown represent the mean ± 1 SD of duplicate wells and are representative of 3 independent measurements.