PRF1 and leukemia: Further, leukemic BM ST2+ Treg cell numbers were positively correlated with expression levels of CD8 T cell exhaustion markers (PD-1 (gating strategy in Supplementary Fig. 4B), TIM3, PD-1 and TIM3, CTLA4, LAG3, and TIGIT) (Fig. 3D) and negatively correlated with Tbet, IFNγ (gating strategy in Supplementary Fig. 4B), CD107a (T cell degranulation marker), and GZMB/perforin cytolytic molecules in both models (Fig. 3E, MLL-AF9 leukemia and Supplementary Fig. 8A, B, DNMT3A/FLT3ITD leukemia).