Inhibition of fibrinogen binding to α_IIbβ₃ reduces IAC-1 binding to α₂β₁ on CVX-stimulated platelets in plasma. (A) Flow cytometric experiments with FITC-labeled IAC-1, FITC-labeled monomeric collagen, and PE-labeled anti–P-selectin, binding to resting platelets (□) or to CVX-stimulated platelets in the absence (▪) or presence (⊡) of 1 μg/mL aggrastat. Data are expressed as the mean ± SEM of at least 3 independent experiments. (B) Representative tracings of the experiments depicted in panel A with the binding of FITC-labeled IAC-1 (left panel) and PE-labeled anti–P-selectin (right panel) to resting platelets (⊡) or to CVX-stimulated platelets in the absence (black line) or presence (gray line) of aggrastat. In all experiments, saturating concentrations of fluorescent antibodies were used.