Effect of MoAb 724 on ¹²⁵I-vWF binding to platelets. Binding of ¹²⁵I-vWF (0.5 μg/mL) to fixed platelets (10⁸/mL) was performed in the presence of ristocetin (0.6 mg/mL) and varying concentrations of either MoAb 418 (•) or MoAb 724 (▪). Results were expressed as specific binding to platelets after subtraction of nonspecific binding in the absence of ristocetin. Means ± SEM were calculated from three experiments in duplicate. In the presence of MoAb 724, ¹²⁵I-vWF binding to platelets was significantly enhanced compared with MoAb 418 (*P< .01).