Inhibitory effects of anti-GPIb mAbs.

Effects on ristocetin-induced (0.3 mg/mL) (A) and botrocetin-induced (0.25 μg/mL) (B) vWF binding to a rGPIbα fragment. mAbs 24G10 (●) and 6B4 (▴) blocked ristocetin-induced binding dose dependently, whereas mAbs 27A10 (▿), 12G1 (■), and 12E4 (⋄) inhibited the binding only moderately. mAbs 27A10, 12G1, and 12E4 did not block the botrocetin-induced binding, in contrast to mAbs 6B4 and 24G10. mAb 26D1 (control, ▪) had no effect when both modulators were used. Binding of vWF was detected with HRP-labeled anti-vWF antibody. Data are the mean of 2 experiments.