Shear-induced platelet aggregation of rvWF-WT and type 2B rvWFs.

Washed platelets (0.5 × 10⁸/mL), rvWF-WT (open bars), -L697V (diagonal hatched bars), -R578Q (black bars), -V553M (gray bars), -M540MM (vertical hatched bars), or -V551F (horizontal hatched bars) were incubated without shear (panel A) or were exposed to 200 seconds^-1 (panel B) or to 4000 seconds^-1(panel C) for 5 minutes at 20°C. DSP was expressed as outlined in the legend to Figure 4. Means ± SEM were calculated from 3 experiments performed in duplicate. P values were calculated by Student t test on paired samples of mutant versus rvWF-WT, as described in the “Materials and methods” section. *P < .05, **P < .001, ***P < .005. DSP of all type 2B rvWFs increased with shear, reaching similar values at 4000 seconds^-1 twofold to threefold higher than rvWF-WT.