oIL-2Rβ Tregs maintain graft-versus-leukemia response. (A-C) Tumor growth and elimination (A-B) and survival (C) are shown for the BALB/c mice injected with A20^luc/yfp+ (2 × 10⁵) leukemia cells at the time of TCD BM transplantation with or without (purple) oIL-2Rβ Tregs and treated with oIL-2 (green) or PBS (blue). Tcon cells were administered 2 days after allo-BMT at a ratio of 5:1 (Tcon:Treg). (D) Frequency of enhanced GFP⁺ MLL-AF9 cells in the PB at various time points after allo-HSCT. Student t test with Bonferroni correction for multiple comparisons was used for statistical analysis. Log-rank test was used to analyze survival curves. Error bars indicate the SD of the mean. ∗P < .05; ∗∗P < .01; ∗∗∗P < .001; ∗∗∗∗P < .0001. Results are pooled from 4 independent experiments with a total of 5 mice per group (oIL-2, n = 20; PBS, n = 21). Survival curves were plotted using the Kaplan-Meier method and compared using a log-rank test. allo-BMT, allogeneic bone marrow transplantation.