Effect of varying doses of cyclodextrin treatment on cholesterol depletion and TF-VIIa activity in fibroblasts. Monolayers of WI-38 cells were treated with varying doses (1 to 10 mM) of mβCD (A-B) for 45 minutes. At the end of 45 minutes, cells were washed and used for determining cholesterol content (A) or cell surface TF-VIIa activity by adding factor VIIa (10 nM) and factor X (175 nM) to the monolayers (B). (n = 4 to 6, mean ± SE). * denotes significantly differs (P < .05) from the control (untreated cells). Panel C depicts the time course of factor X activation by TF-VIIa in control and cholesterol-depleted cells (10 mM mβCD treatment for 45 minutes). Two different concentrations of factor X were used, 175 nM (circles) and 1 μM (squares). Filled symbols represent control cells, and open symbols represent mβCD-treated cells.