Cell death in the absence of stimulation. (A) T-cell cultures described in Figure 5 were stained weekly with annexin V and 7-AAD during the cultures to monitor cell death and survival in the absence of antigenic stimulation. Graphs show the percentage of annexin V–positive and 7-AAD–negative cells, as indicated by the numbers in the graphs, at day 15, 22, 29, 43, 50, and 57 in the cultures of MoT-72 and hTERT-transduced MoT-72. Top row: 7-AAD staining and forward scatter plot indicating the cell population (R2) of cells impermeable to 7-AAD that was analyzed, and IgG-PE control staining. Similar results were obtained with CD8⁺ T-cell clone AKR103 (not shown). (B) Apoptosis induced by rhIL-2 withdrawal during 24 hours. hTERT-transduced MoT-72 cells and untransduced cells cultured in rhIL-2 for 14 days were washed and cultured overnight in the presence or absence of rhIL-2. Graphs show the presence of apoptotic cells after 24 hours. Numbers in the graphs indicate the percentage of annexin V–positive cells.