Figure 2.

Interleukin-7 (IL-7) protects human effector/memory T cells from apoptosis and inhibits caspase-3 activation. (a) Cells at day 8 (0 hr time-point) were cultured under deprived conditions in the presence or absence of IL-7 (2 ng/ml) or IL-2 (50 U/ml) for different periods of time. Apoptosis was determined using Annexin V/7-aminoactinomycin D staining and flow cytometry analysis. The results are presented as mean percentages (± SE) of Annexin-V-positive cells from three independent experiments performed in triplicate with T cells isolated from different blood donors. *P < 0·05 between IL-7-treated or IL-2-treated samples and non-treated (medium) samples. (b) IL-7 inhibits caspase-3 activation. Effector/memory T cells were cultured under deprived conditions in the presence or absence of IL-7 for different periods of time. Cells at day 8 (0 hr time-point) were used as controls. Whole cell lysates were prepared and activation of caspase-3 was determined by immunoblot analysis using an anti-caspase-3 monoclonal antibody recognizing both pro-caspase-3 (p32) and the active form of caspase-3 (p17). The blot was stripped and re-probed with anti-β-actin monoclonal antibody to ensure equal loading. Results are representative of five independent experiments performed with T cells from different blood donors.