Influence of vWF surface density and the role of the GP V subunit. LβIXV and LβIX cells with a high receptor density (geometric mean >800 fluorescent units) were evaluated on surfaces prepared using vWF solutions with concentrations ranging from 250% to 750% of normal vWF plasma concentration. The mean velocity (A) and the total number (B) of rolling cells were determined at a wall shear stress of 10 dyn/cm². Values are the mean ± SEM, n = 4 to 8.