(A–C) B6 mice were injected with B16 melanoma tumor s.c. on day −12 and then irradiated (6 Gy) on day −1. On day 0, mice were adoptively transferred with 2×106 Tc1 CD8+ effector T cells. (A) Donor cells in blood on day 5 (n = 4–5, ** p < 0.01, *** p < 0.001; representative of 2 independent experiments). (B) Survival data (n = 16–20, *** p < 0.001 for No ACT vs. IL-15−/− Tc1 + αIL-7 mAb and **** p < 0.0001 for Tc1 IL-15−/− vs. Tc1) and (C) tumor growth curves are pooled from 2 independent experiments of 8–10 mice. (D) 5×106 Tc1 cells were injected into irradiated WT or IL-15−/− mice with or without administration of the indicated antibodies. Anti-IL-7 mAb was given at either 100ug or 500ug per injection. After 77 days, the frequency of donor cells in the peripheral blood was measured. Results are representative of 2 independent experiments.