Endothelial cell adhesion to purified WT-rvWF, RGGS-rvWF, or ΔA1-rvWF. Endothelial cells were added to microtiter wells precoated with rvWF. After 2 hours of incubation at 37°C, adherent cells were fixed with paraformaldehyde and stained. Quantitation of adhesion was performed with a real time digital imaging processing system. Adhesion to BSA (20 μg/mL) was subtracted from the data. Results were expressed as the percentage of adherent cells relative to the total number of cells. The mean ± SEM were calculated for three experiments performed in duplicate. Adhesion of nonstimulated cells is shown using solid symbols and adhesion of TNFα-stimulated cells with open symbols. Adhesion to increasing concentrations of purified rvWF: (A) WT-rvWF (•, ○), (B) RGGS-rvWF (▴, ▵); and (C) ΔA1-rvWF (▪, □).