Fig. 4: Adoptive transfer of ST2-deficient T_reg cells increases CD8 T cells count, Tbet/IFNγ expression, and WT1 tumoral specificity while decreasing CD8 T cells exhaustion to decrease AML growth.

A Schematic of the MLL-AF9 leukemic model with the adoptive transfer of 20% WT or ST2^−/− T_reg cells among total T cells. B Kaplan–Meier survival analysis of the adoptive transfer leukemic model as described in (A) (10⁵ MLL-AF9 ^eGFP leukemic cells per mouse, n = 20). Log-rank test was used to compare groups. C Representative flow plots showing the frequencies of MLL-AF9^eGFP in the malignant BM niches on day 10 post leukemic cell challenge (10⁵ per mouse), and the statistical analysis results for the indicated days (n = 5 on day 5, n = 8 on day 10, and n = 5 on day >20). Statistically analyzed frequencies of CD3⁺CD8⁺ (n = 4) (D), CD8⁺PD-1⁺ (n = 5) (E), CD8⁺Tbet⁺ and CD8⁺IFNγ⁺ (n = 5) (F) T cells in the malignant BM niches on the indicated days post MLL-AF9 leukemic cell challenge (10⁵ per mouse). G Schema of non-irradiated MLL-AF9 leukemia model in either WT or ST2^−/− mice followed by in vivo depletion of T_regs with an anti-CD25-Ab (Clone PC61) on day 1, and day 7 for a total dose of 500 µg/mouse; the control group received an isotype-Ab (Rat IgG1). Kaplan–Meier curves for survival in the four groups: both survival of T_reg-depleted WT mice (green curve) and ST2^−/− mice (blue curve) are significantly extended in comparison to the WT mice receiving control isotype-Ab (red curve), but both differ between them. T_reg-depleted ST2^−/− mice (black curve) displayed significantly improved survival as compared to T_reg-depleted WT mice (green curve). Frequencies of eGFP⁺ MLL-AF9 cells in the BM and of T_reg cells in the BM in the 4 groups over time (n = 4 per time point). The data are presented as means ± s.e.m. (error bar) compared using two-sided unpaired t-test or ANOVA with post-hoc Bonferroni t-test for three groups or more (C–G), and Kaplan–Meier curves compared using log-rank test (B, G). P values are presented in the figure. Source data are provided as a file.