FIGURE 9. N-acetyl-l-cysteine protects against FasL-induced GSH depletion and apoptosis.

Apoptosis was induced in Jurkat cells by incubation with 25 (A) and 50 (B–E) ng/ml FasL for 4 h. MK571 (50 µm) and high extracellular NAC medium (+NAC) were added at the time of FasL stimuli. A, changes in GSH_i were determined by FACS. Populations were gated according to their GSH_i levels on an mBCl fluorescence versus forward scatter plot as explained under "Experimental Procedures." FasL-induced apoptosis was assessed by (B) phosphatidylserine externalization and loss of plasma membrane integrity; (C) simultaneous detection of cleaved caspase 3 and PARP; (D) DIC images depicting nuclear condensation, plasma membrane blebbing, and cellular fragmentation; and (E) immunoblot detection of full-length and cleaved forms of execution caspases 3, 6, and 7, as well as their substrates PARP and α-fodrin. Results are expressed as in Fig. 5. Plots, images, and blots are representative of n = 3 independent experiments.