hTERT-transduced T cells are more resistant to oxidative stress than untransduced cells. Untransduced and hTERT-transduced cells of Th1/Th0-like clone MoT-81, Th2 clone BOY JF157, or CD8⁺ clone AKR103 taken 2 weeks after stimulation were depleted of dead cells and treated with H₂O₂ at the indicated concentrations in the presence of FeSO₄ and rhIL-2. The presence of apoptotic cells was analyzed after 5 hours, 24 hours, or 48 hours of incubation by annexin V binding. In parallel cultures, apoptosis was induced by treatment with dexamethasone. Graphs show the percentage of annexin V–positive and 7-AAD–negative (apoptotic) cells after overnight incubation. (A) Percentage of apoptotic cells of clone MoT-81 after 48 hours of incubation (left panel) and clone AKR103 after 24 hours of incubation (right panel). Graphs show representative results of 2 (MoT-81) or 3 (AKR103) independent experiments. The graphs in the bottom row indicate the percentage of apoptosis induced by dexamethasone treatment. (B) Average percentage of apoptotic cells and standard deviation of CD4⁺ BOY JF157 T cells after 24 hours (left graph) or 48 hours (right graph) of incubation with H₂O₂, as measured in 3 independent experiments. ○ indicates BOY JF157; •, BOY JF157 hTERT.