Effect of PECAM-1 interactions in collagen (GP)VI-selective ligand, CRP-induced platelet aggregation.

Washed human platelets were pre-incubated with FcγRII-blocking antibody IV.3 Fab (10 μg/mL) followed by recombinant human PECAM-1–immunoglobulin chimera (0-100 μg/mL) for 5 minutes with stirring. Platelets were then stimulated with collagen-related peptide (2 μg/mL). Platelet aggregation was monitored by changes in light transmission. The ordinate represents percentage changes in light transmission. Data are representative of 3 experiments. (B) Percentage CRP-induced platelet aggregation after pre-incubation with increasing doses of recombinant human PECAM-1–immunoglobulin chimera (0-100 μg/mL) (white bars) or mutant K89A human PECAM-1–immunoglobulin chimera (0-100 μg/mL) (black bars) or human IgG (0-100 μg/mL) (gray bars) represented by mean ± SD of the mean of 3 separate experiments with different blood donors. **Significantly differentP < .0001, according to Student unpaired ttest from 3 separate experiments.