Comparison of TF de-encryption in different cell types. (A) HL60 and U937 cells were stimulated for 6 hours with 1 μM PMA to induce TF expression. The PMA-treated cell lines and THP1 and MDA-MB231 cells were incubated with 10 μM ionomycin (IM), 100 μM HgCl2 (Hg) or dimethylsulfoxide vehicle control for 30 seconds and TF procoagulant activity measured by clotting time or by analysis of progress curves of factor X activation.1 Both methods of measuring TF procoagulant activity gave equivalent results (data not shown). Cells were also preincubated for 10 minutes with 10 mM (HL60, U937, and MDA-MB231 cells) or 50 mM (THP1 cells) MMTS before the addition of ionomycin or HgCl2. Results are expressed as fold change in TF activity compared with DMSO-treated cells. The bars and errors are the means plus or minus the SE of at least 3 determinations. (B) MDA-MB231 cells at approximately 80% confluence were incubated with 50 mM GSH or DTT or 10 mM MMTS for 15 minutes at 37°C and the cells washed twice with HEPES-buffered saline. Cell viability was determined using CytoTox-One Reagent (Promega, Madison, WI). The bars and errors are the means plus or minus the SE of 3 determinations.
