ADP receptor antagonism partially prevents intravascular TF activity. (A) Neutrophils promote activation of TF in suspensions of collagen-activated platelets. Isolated platelets (2 × 107) and neutrophils (2 × 106) were suspended in 170 μL resuspension buffer and stimulated with collagen (5 minutes, 37°C). Factor Xa formation was measured by a chromogenic substrate. The monoclonal anti-TF antibody and the isotype control antibody were present at 10 μg/mL. Means ± SDs; n = 4. *P < .05 (versus platelets plus neutrophils). (B) Intravascular TF activity is diminished by ADP receptor antagonists. TF activity in suspensions of collagen-activated platelets and neutrophils was determined as described above. AR-C69931MX and MRS-2179 were present at the indicated concentrations. Means ± SDs; n = 3to5.*P < .05 (versus collagen alone).
