Lactadherin binding to platelets and platelet-derived microvesicles. Washed human platelets were treated with (A) buffer only, (B) collagen (50 μg/mL), or (C) a combination of thrombin (0.1 U/mL) and collagen (50 μg/mL), and FITC-lactadherin (5 μg/mL) and a PE-labeled anti-CD42b (2.5 μg/mL) were added. The generation of microvesicles was analyzed by flow cytometry as described before.6 To resolve the platelets and platelet-derived microparticles from background scatter, only CD42b+ events were analyzed for forward and side scattering. The gates for microvesicles (gate M) and intact platelets (gate P) were set with the use of isolated microvesicles and unstimulated platelets, respectively. Platelets and microvesicles were analyzed separately for the expression of phosphatidylserine by 5 μg/mL FITC-lactadherin (D,E).