ADP pathway contributes to establish platelet-leukocyte adhesions promoting TF function. (A) Platelet-neutrophil adhesions support platelet TF activity. Isolated platelets (2 × 10⁷) and neutrophils (2 × 10⁶) were stimulated with collagen (5 minutes, 37°C) and, subsequently, the factor Xa generation was assessed. Under similar conditions, the anti–P-selectin antibody (10 μg/mL) was added. Means ± SDs; n = 4. *P < .05 (versus collagen alone). (B) Generation of platelet-neutrophil conjugates is reduced by inhibition of P-selectin–mediated adhesion. Conjugate formation was established by determining the number of events being positive for CD42b and CD66b. The anti–P-selectin and isotype control antibody were added at 10 μg/mL. Means ± SDs; n = 4. *P < .05 (versus collagen alone). (C) Formation of platelet-leukocyte conjugates is prevented by inhibition of the ADP receptors. The number of CD42b⁺ leukocytes among the total fraction of CD45⁺ cells was determined in collagen-activated whole blood in the absence or presence of MRS-2179 (1 mM) and AR-C69931MX (10 μM). Means ± SEM; n = 5to8.*P < .05 (versus collagen alone).