Effect of FcγR signaling pathways on KKO-induced platelet and fibrin accretion. FcγRIIA, FcγRI, FcγRIII, and FcγRIIA plus FcγRI signaling was blocked in whole blood samples as in studies shown in Figure 2 for (A) platelet accretion, and (B) fibrin generation. Relative platelet accretion and fibrin generation are expressed as the ratio of results from samples blocked with specific mAb to samples pre-incubated with isotype control. Mean ± 1 SEM is shown. Dotted line represents the relative value for the isotype control; values below the dotted line means inhibition after blockade of the indicated FcγR compared with isotype control with P values shown relative to that control. Significance was determined using two-tailed Student t tests when comparing FcγR to the isotype control, each stimulated with PF4 and KKO. N = 10 with samples from 5 donors. (C-D) are as (A-B) respectively, but with isolated monocytes that were then used to reconstitute whole blood as in Figure 3. n.s., not statistically significant between blocking FcγRIIA and blocking FcγRIIA plus FcγRI.