Figure 2.

Induction of proliferation and prevention of apoptosis by IL-7 and IL-15. (a) Purified CFSE-labelled CD8⁺ T cells were incubated with graded doses of recombinant human IL-7 or IL-15 for 6 days and the percentage of cells that had undergone division measured (one representative experiment of three). (b) Purified CD8⁺ T-cell subsets were stimulated with high or low doses of IL-7 or IL-15 and proliferation measured by [³H]-thymidine incorporation on day 6. (c) Apoptosis of purified subsets in the presence or absence of IL-7 or IL-15 was measured by annexin V–FITC staining on day 6 (mean ± SE of data from six individuals). *Indicates P ≤ 0·05 compared to the same cells cultured in medium alone.