PAF plays a major role in supporting neutrophil adhesive behavior on the surface of thrombi. Citrated whole blood was perfused over a (A,B) VWF (100 μg/mL) or (C,D) collagen type I (2 mg/mL) for 5 minutes at 1800 s⁻¹ to form thrombi followed by perfusion of cell-free Tyrode buffer supplemented with 1 mM CaCl₂/MgCl₂ for 5 minutes. Isolated neutrophils (1 × 10⁶/mL) resuspended in supplemented Tyrode buffer were pretreated with Me₂SO (Control) or PAF receptor antagonists WEB2086 (30 μM), PC-4248 (PC; 5 μM), CV-3988 (CV; 5 μM), or the LTB₄ receptor antagonist, LY255283 (LY; 20 μM), for 5 minutes prior to perfusion over VWF or collagen thrombi. Neutrophil-thrombus interactions were visualized by phase contrast microscopy and the proportion of adherent neutrophils forming firm adhesion contacts (A,C) and spreading (B,D) was quantitated. Results are presented as means (± SEM; n = 2-4). *P < .05, **P < .01, ***P < .001.