Effect of anti–integrin α₂mAb and GPIb antagonist on the binding of FITC-conjugated aggretin to HUVECs. (A) HUVECs (1 × 10⁶ cells) were incubated with various concentrations of FITC-conjugated aggretin or FITC-conjugated BSA for 30 minutes and then analyzed by flow cytometry. Specific binding (⋄) was calculated by subtracting the nonspecific binding (○, as probed by FITC-BSA) from total binding (, as probed by FITC-aggretin). A representative one of 3 similar results is shown. (B) The binding of FITC-BSA to PBS-treated HUVECs is shown as a dotted line. HUVECs (1 × 10⁶ cells) pretreated with mAb A2-IIE10 (50 μg/mL, thick line) or agkistin (50 μg/mL, thin line) were incubated with FITC-conjugated aggretin (1 μM) and analyzed by flow cytometry. The binding of FITC-aggretin to PBS-treated HUVECs is marked as the gray area. Nonspecific binding was carried out by incubating HUVECs with FITC-conjugated BSA (1 μM). Similar results were obtained in at least 3 separate experiments. (C) Quantitative analyses of FITC-aggretin and FITC-BSA presented as mean fluorescence intensity. Data are presented as mean ± SEM (n = 3). **P < .01 as compared with that of control.