Ezh2 regulates the survival and expansion of alloantigen-activated T cells in a cell-autonomous manner. (A) Donor T cells were isolated from the spleen of WT and T-KO mice (before transplantation) and of allogeneic BMT BALB/C recipients 7 days after transplantation (after transplantation) to measure their expression of Foxp3. (B) CD4⁺CD25⁺ Tregs were isolated from WT and T-KO B6 mice and added to the wells of a 96-well plate containing CD25^– CD4⁺ T cells derived from B6/SJL mice (CD45.1) at ratios as indicated. Seventy-two hours later, the recovery rate of proliferating CD45.1⁺ CD4⁺ T cells was analyzed. (C) B6 WT T cells, T-KO T cells, or T-KO T cells depleted of CD4⁺CD25⁺ Tregs were transplanted together with TCD BM into irradiated BALB/C recipients to induce GVHD. The survival was monitored over time. ○, n = 5; ▪, n = 5; ▲ n = 5; △ n = 10. (D) WT T cells derived from B6/SJL mice (CD45.1⁺) and T-KO T cells derived from B6 mice (CD45.2⁺) were mixed at a ratio of 1:1 and transplanted with TCD BM into lethally irradiated BALB/C recipients. Seven days later, cells were recovered for flow cytometry analysis. Dot plots show the fraction of donor WT and T-KO T cells. **P < .01, ***P < .001. Data shown in (A), (B), and (D) are from 3 to 5 mice per group. Data are representative of 2 independent experiments. Error bars indicate mean ± SD.