Contribution of CLEC-2 and GPVI to platelet activation by hemin. (A) Hemin-induced platelet aggregation in WT mice. Washed murine platelets were stimulated with 5 concentrations of hemin (0, 2.5, 5.0, 7.5, and 10 μg/mL). (B) Hemin-induced murine platelet aggregation using 4 concentrations of hemin (0, 5.0, 7.5, and 10 μg/mL) in WT (blue), CLEC-2–depleted (red), FcRγ-deficient (green), and CLEC-2–depleted FcRγ-deficient (purple) mice. The representative aggregation curves of platelets treated with 7.5 µg/mL hemin are shown. (C) Blocking effect of 0.8 µg/mL Co-HP or 1% dimethyl sulfoxide/PBS (control) on hemin (10 μg/mL)- or rhodocytin (Rhod) (5 nM)-induced platelet aggregation in FcRγ-deficient mice. The representative curves (left and middle) and quantifications of maximum light transmission (right) are shown. (D) Blocking effect of 10 µg/mL anti-GPVI antibody (ab) or control rat IgG (control) on hemin (10 μg/mL)- and CRP (0.125 µg/mL)-induced platelet aggregation in CLEC-2–depleted mice. The representative curves (left and middle) and quantifications of maximum light transmission (right) are shown. Data in the bar graphs (panels A-D) are mean ± standard deviation; n = 3. *P < .05, **P < .01, ***P < .001. Tukey’s multiple-comparison test was used for panels A and B, Student t test was used for panels C and D.