Pharmacologic inhibition of integrin α2β1 and/or glycoprotein VI reduces deposition of human platelets on collagen under flow. (A) Whole blood was treated with 10 μg/mL of the blocking anti-α2 antibody 6F1 (▪), the blocking anti-GPVI antibody 11A12 (□), both 6F1 and 11A12 (▦), or 20 μg/mL mouse IgG (mIgG; ▨) for at least 30 minutes prior to being perfused over a collagen-coated surface (“undiluted”). To facilitate comparison with the mouse platelet studies shown in Figure 1, this experiment was also performed using human blood diluted with an equal volume of Tyrode buffer (“diluted”). The results shown are the mean ± SEM (n = 4-5). Statistically significant inhibition was seen with all treatments (P < .05) at all shear rates with undiluted blood, and at 1300 s–1 with diluted blood. (B) Representative phase-contrast images after 4 minutes of perfusion of heparinized whole human blood over an immobilized collagen surface. The lines seen in the upper left portions of some panels are visual artifact and do not arise due to abnormalities in the collagen-coated surface.
