The role of endogenously released PF4 in APC generation and survival after thrombin injection. (A) APC generation; basal (open bar) or 10 min after thrombin injection (black bars) in WT mice. Prior to thrombin, the noted recombinant chemokine or PBS only (control) was injected (IV) at 7.5 mg/kg for hPF4 and 10 mg/kg for mPF4 and NAP-2. The mean (± 1 SD) are shown. n = 5 to 6 per arm. *P < .001 relative to control. (B) Thrombin injections studies were done as in (B) in WT (n = 15), mPF4^−/− (n = 16), hPF4⁺ (n = 22), PC^+/− (n = 5) and PC^+/−/hPF4⁺ (n = 7) mice. The means (± 1 SD) are shown. *P < .001 and **P < .003 relative to WT, and ***P < .003 comparing PC^+/−/hPF4⁺ and PC^+/− mice. (C) Survival after thrombin injection as in (B) of WT (n = 15), mPF4^−/− (n = 21), hPF4⁺ (n = 22), PC^+/− (n = 12) and PC^+/−/hPF4⁺ (n = 7) mice. APC was assayed in surviving animals. P < .001. Statistical analysis was performed using Fisher exact test.