First, an adoptive transfer in a lethally irradiated mice that contained only AML cells, supportive BM cells, T cells and Treg cells and does not contain other immune cells or mature myeloid cells showed that mice transplanted with ST2−/−Foxp3eGFP+ Treg cells versus WT Foxp3eGFP+ Treg cells had an extended survival, less AML growth, and an increase in CD8+Tbet+ and CD8+IFNγ+ T cells and less CD8+ PD-1+ exhausted T cells. The gene discussed is CD8A; the disease is acute myeloid leukemia.