Figure 4.

Commitment to Fas-induced cell death occurs at an early time point relative to loss of viability as measured by ΔΨ_m or dye exclusion. (A) Jurkat T cells were treated with anti-Fas for 6 hr at which point one-half of the cells were removed, washed three times in fresh medium, and resuspended in fresh medium. The number of total viable cells was determined, as described in Fig. 3, at indicated time points. The cells which remained continually in anti-Fas are represented by open symbols and solid lines while the washed cells are represented by filled circles and dashed lines. The data are presented as the mean ± standard deviation of six independent determinations and are representative of two independent experiments. (B) Jurkat T cells were treated as described in A, and viability and ΔΨ_m were monitored by staining cells with propidium iodide (y axis; PI) and rh123 (x axis; Rh123) at the indicated time points. The data represent one of three replicate samples from a representative experiment. The data are representative of four independent experiments.