FIGURE 1. Reactive oxygen species generation correlates with changes in intracellular glutathione, GSH_i.

Reactive oxygen species formation was assessed by FACS using DHR for H₂O₂ detection; DHE for superoxide anion (${}^{•}\mathrm{O}_2^{-}$); HPF for hydroxyl radical (^•OH⁻); and BODIPY® FL EDA, for LPO. Changes in intracellular glutathione concentration GSH_i were determined by FACS using the thiol binding dye monochlorobimane, mBCl. For the induction of apoptosis, Jurkat cells were incubated with FasL for 4 h at the concentration indicated. Data are expressed as changes in ROS-sensitive dye fluorescence represented by frequency histograms (upper panels in A–D) or in contour plots versus changes in mBCl fluorescence (GSH_i) (lower panels in A–D). In contour plots, the quadrant center was set at the mean fluorescence intensity for mBCl and the corresponding ROS dye, as a reference to indicate basal levels of GSH_i and ROS. Populations were gated and represented according to the differences in ROS levels. Plots are representative of n = 3 independent experiments.