Bacteria induce tyrosine phosphorylation of FcγRIIA that is dependent on αIIbβ3 activation. (A) Tyr phosphorylation of FcγRIIA and downstream mediators during bacteria-induced platelet aggregation in plasma. Cell lysates were collected at time of full aggregation; IPs were performed for FcγRIIA, Syk, and PLCγ2. As previously described,37 FcγRIIA coprecipitated during Syk IP and, therefore, phosphorylated Syk and FcγRIIA were detected in the same gel. (B) Effect of αIIbβ3 inhibitor Integrilin on FcγRIIA phosphorylation during bacteria-induced platelet activation. Aggregation reactions were performed in plasma in the presence or absence of Integrilin (9 μM); cell lysates were collected at time of full aggregation, or equivalent times in the case of Integrilin-treated samples where aggregation was inhibited. IPs for FcγRIIA were performed; tyrosine phosphorylation was detected by western blot. Representative results of 3 independent experiments are shown.
