TF inhibition prolongs the onset and reduces the rate of thrombin generation and clot formation, resulting in a less dense fibrin network. Recalcified (10mM, final) normal pooled PFP was added to confluent HUVECs and TNFα-treated HUVEC monolayers in the presence of anti-TF antibody (10 μg/mL anti–human TF antibody) or IgG control. (A) Thrombin generation was measured by calibrated automated thrombography. Data (± SD) show the average of 5 separate experiments. (B) Fibrin polymerization was monitored by turbidity at 405 nm. Data (± SD) shown are from 1 experiment, representative of 4 separate experiments. Symbols for panels A and B are HUVECs plus: IgG, (■); anti-TF, (□); TNFα+IgG, (▴); TNFα+anti-TF, (▵). (C) Three-dimensional projections (146 μm × 146 μm, xy) show clot architecture in 10-μm stacks 0 to 10 μm from the surface of unstimulated or TNFα-stimulated HUVECs in the presence or absence of anti-TF, as indicated. Each image is from 1 experiment, representative of 4 independent experiments. (D) Fibrin density (± SD) was measured as described in “Methods.” (E-F) Clotting was initiated in the presence of tPA (250 ng/mL) and the time to peak and peak turbidity were calculated from resulting turbidity curves. Data (± SD) show the average of 9 independent experiments. *P < .05 versus unstimulated HUVECs.