Fig. 3.
Citrulline-specific activation of platelets is FcγRIIa-dependent. Platelets were isolated from healthy donors. ACPA plate-bound immune complexes were generated by incubating ACPAneg and ACPApos plasma on wells coated with citrulline- or arginine-containing peptides. Representative examples of citrulline-specific increase in P-selectin expression and sCD40L release are shown in a and d, respectively. b and e These effects are still present after correcting for aspecific binding by calculating the citrulline/arginine ratio. c and f Summaries of three independent experiments. Pre-incubation of platelets with a blocking antibody directed against FcγRIIa abolished the citrulline-specific induction of P-selectin (g) and sCD40L release (h). ACPA anti-citrullinated protein antibodies, CD62P P-selectin, FcγRIIa low-affinity immunoglobulin G receptor, sCD40L soluble CD40 ligand. *P < 0.05