PF4 and infection: In fact, WBC uptake depends on the enhanced influx of granulocytes to the infection/inflammation site mediated via immunological binding to cellular antigens and chemotactic peptides (f-Met-Leu-Phe) [22,23], cytokines (interleukin 1 (IL-1), IL-8, Platelet factor 4 PF-4) [24,25,26], and complement factors (C5a, C5adR) [27].