Preservation of allogeneic GVL effects in IL-12–treated mice. Results from three individual experiments are shown in each column. B10 (H-2^b) mice were lethally irradiated on day 0. (A through C) Nonleukemic mice received 5 × 10⁶ TCD B10 BMC and 15 to 18 × 10⁶ B10 spleen cells with or without IL-12 treatment (Syn BMT +/− IL-12), or 5 × 10⁶ TCD B10 BMC plus 10 × 10⁶ A/J BMC and 15 to 18 × 10⁶ A/J spleen cells with (Allo BMT + IL-12) or without (Allo BMT) IL-12 treatment. (D through F ) Leukemic recipients in the same experiments received 5 × 10⁶ TCD B10 BMC and 15 to 18 × 10⁶ B10 spleen cells alone with (Syn BMT + EL4 + IL-12) or without (Syn BMT + EL4) IL-12 treatment, or 5 × 10⁶ TCD BMC plus 10 × 10⁶ A/J BMC and 15 to 18 × 10⁶ A/J spleen cells with (Allo BMT + EL4 + IL-12) or without (Allo BMT + EL4) IL-12 treatment. All leukemic recipients received 500 H-2^b EL4 cells on the day of BMT.