TF expression in HUVECs induced by TNF.

TNF induces TF activity in a dose-dependent manner (A). TF was quantitated by a 1-stage clotting assay as described in “Materials and methods.” Incubation of ECs with increasing concentrations of TNF from 1 pg/mL to 1 μg/mL for 3 hours demonstrated increased TF activity with doses above 1 ng/mL. Significant TF activity was observed after a 3-hour exposure to 1 μg/mL TNF (B).