Comparative induction of HUVEC TF activity by phagocyte oxidants. (A) Dose response analysis of phagocyte oxidants. HUVEC monolayers were exposed to 0 to 100 μM reagent HOCl, HOSCN, or H₂O₂ for 4 hours in M199 medium with 1% FBS, medium was replaced with HBSA with 10 μM ionophore A23187, and scraped freeze-thawed lysates were assayed for TF activity using a 2-stage clotting assay. (B) Time course of phagocyte oxidant induction of TF activity. HUVEC monolayers were exposed to either buffer, 50 μM reagents HOCl, HOSCN, or H₂O₂, for 0 to 8 hours as described for panel A, and assayed for TF activity at the indicated time points. (C) Substrate-dependent TF activity induction by EPO. HUVEC monolayers were overlaid with 100 nM EPO in HEPES/Hanks buffer (+ EPO) or the same buffer to which 1 mM NaSCN (+ EPO + SCN^–), 1 mM NaBr (+ EPO + Br^–), or 1 mM NaNO₂ (+ EPO + NO₂^– was added. The indicated final concentrations of H₂O₂ were added, monolayers incubated 30 minutes, supernatant buffer replaced with M199 with 10% FBS, and freeze-thawed cell lysates assayed for TF activity by one-stage clotting assay after a further 5 hours of incubation. All data are shown ± SD.