Specific FITC-collagen binding still occurs to agonist-stimulated, fixed platelets. (A) Human platelets were treated with control buffer or 25 μM TRAP for 2 minutes, fixed with PFA, washed, and incubated with 10 μg/mL FITC-collagen in the presence of control buffer or 1 mg/mL unlabeled collagen (Col) for 30 minutes at room temperature. Data shown are normalized mean fluorescence ± SEM from one experiment, representative of 4 similar experiments. P < .05 for unlabeled collagen versus TRAP only. (B) Agonist-treated or control, fixed murine platelets were preincubated with hamster antimouse α2-blocking mAb or control IgG (5 μg/mL) before incubation with FITC-collagen. Data are average normalized mean fluorescence ± SEM from 3 independent experiments. P < .05 for α2-blocking mAb compared with control IgG.
