Fig. 3: Caspase activity parallels glycolysis and CD25 expression in T cells

a–c T cells were activated with anti-CD3/CD28 for 2 days and cultured in IL-2 for a third day. T cells were then washed and cultured in IL-2 or IL-15 for an additional 7 days. a Baseline extracellular acidification rate (ECAR) was measured by extracellular flux analysis on days 0, 6, and 10 (two-way ANOVA with Tukey’s correction; NS not significant; *p < 0.01; mean ± S.E.M. of means from three independent experiments). b CD25 expression measured daily by flow cytometry (the graph is representative of two independent experiments). c Caspase activity was measured daily by DEVD rhodamine release (mean ± S.D. of three replicates within the one experiment shown. The graph is representative of two independent experiments). d Anti-CD3/CD28-activated T cells were cultured in IL-2 or IL-15 for 3 days. For a positive control, IL-2-cultured T cells were incubated with FasL for 1.5 h to induce caspase-3 activity and cell death. Cells were stained for intracellular active caspase-3 and analyzed by flow cytometry (the graph is representative of three independent experiments). e, f Purified CD4⁺ T cells were differentiated into Th1, Th2, and Treg subsets by activation with anti-CD3/CD28 for 2 or 3 days along with the appropriate cytokines (see Materials and Methods). T-cell subsets were then cultured for an additional 2 or 3 days in IL-2 according to an established protocol¹¹. e Baseline ECAR was measured by extracellular flux analysis (one-way ANOVA with Tukey’s correction; **p < 0.0001; mean ± S.D. of five replicates within the one experiment shown. The graph is representative of two independent experiments). f Caspase activity was measured by DEVD rhodamine fluorescence (one-way ANOVA; **p < 0.0001; mean ± S.D. of three replicates within one experiment. The graph is representative of two independent experiments)