Inhibition of FcγRIIa-mediated platelet aggregation by anti-PECAM-1 Fab fragments. (A) Washed platelets (3 × 108 platelets/mL) were pretreated with varying concentrations of biotinylated Fab fragments of anti-PECAM-1 (2BD4) (0-10 μg/mL as indicated) and anti-FcγRIIa IV.3 mAb (10 μg/mL) for 5 minutes. Following pretreatment, where indicated cross-linking (XL) was initiated by addition of 10 μg/mL Neutravidin to induce FcγRIIa-mediated platelet aggregation. (B) Washed platelets (3 × 108 platelets/mL) were pretreated with 10 μg/mL biotinylated Fab antibody fragments of mAbs directed to CD151 (11B1), PECAM-1 2BD4, or FcγRIIa (IV.3) for 5 minutes. Following pretreatment, cross-linking was initiated in appropriate cuvettes by addition of 10 μg/mL Neutravidin to induce FcγRIIa-mediated platelet aggregation.
