IL-7 activates TAIL7 cells and promotes cell cycle progression and increased viability. (A) TAIL7 cells were cultured for 72 hours with or without IL-7, and the cell cycle phase distribution was examined by PI staining and flow cytometry. Results are representative of 3 independent experiments. (B) At 72 hours, activation was assessed by flow cytometry, by gating on the live cell population, and by measuring the changes in cell size (forward light scatter [FSC]) and complexity (sideward light scatter [SSC]). The “percentage of activated cells” shown was defined relative to the distribution of the control population (medium alone). Similar results were obtained in 7 independent experiments. (C) At 96 hours, cells were stained with Annexin V–FITC/PI, and the percentage of viable cells was assessed by flow cytometry. Results are expressed as mean and standard deviation of 3 samples for each condition and are representative of 5 independent experiments.