Characterization of hPF4 mice. (A) Total platelet-associated hPF4 expressed per mL of blood in WT animals and the 3 hPF4 transgenic mice lines studied. Controls (Ctl) were platelets from 4 human donors. The mean ± 1 SD is shown for the experiments performed 3 times, each in triplicate. (B) Flow cytometric measurement of CD41⁺–platelet-bound FITC-KKO in the same animals as in panel A measured 10 minutes after intravenously injected FITC-KKO.