Figure 1. The enhanced persistence of IL-12 conditioned CD8⁺ T cells (Tc1) in lymphodepleted hosts is dependent on IL-7.

(A, B) B6 mice were injected with B16 melanoma tumor s.c. on day −12 and then irradiated on day −1. On day 0, mice were adoptively transferred with 2×10⁶ 3-day activated pmel-1 CD8⁺ T cells with IL-12 conditioning (Tc1) or without (Tc0). (A) Survival curves (n = 8, *** p = 0.001 for Tc1 vs. control, p < 0.0001 for Tc1 vs. Tc1 + TBI) and (B) individual tumor growth curves. (C, D), 5×10⁶ Tc1 or Tc0 cells were transferred into mice with or without 6 Gy TBI and Thy1.1⁺ donors were tracked in the (C) peripheral blood over time (n = 5) or (D) in the spleens 7 days post-transfer (n = 5, **** p < 0.0001). (E) As in (D) except cells were transferred into WT B6 or IL-15^−/− mice with or without αIL-7 neutralizing mAb (clone M25; n = 5, **** p < 0.0001). All results are representative of at least 2 independent experiments.