TF induction by phagocyte oxidants in the presence of 10% serum. (A) Total cell lysate TF activity. Monolayers of HUVECs were supplemented with buffer (control), or 50 μM(□), or 150 μM(▪) of reagent HOCl, HOBr, HOSCN, and H₂O₂ in M199 medium with 10% serum and incubated at 37°C for 4 hours prior to assay of TF activity in ionophore-treated cell lysates. (B) TF Western blot. HUVECs were treated as in panel A with 150 μM of the designated oxidant or 10 ng/mL LPS and TF was detected by Western blot. (C) Cell surface TF activity. HUVECs were exposed to either buffer control (□) or 150 μM HOSCN (▪) for the indicated times and harvested into single-cell suspension by trypsinization. A total of 6 × 10⁵ cells were pelleted, washed with HBSA buffer, and then incubated with 6 nM factor VII_a, 600 nM human FX, and 10 mM CaCl₂ at 37°C for 15 minutes. Supernatant fluid X_a activity was quantitated by clotting assay and TF activity derived from a standard curve using recombinant TF in the first stage. All data are shown ± SD.