IL1RL1 and leukemia: Therefore, to further establish the weight of leukemic ST2+ Treg cells in the overall role of ST2 in the BM niche, we used a non-irradiated leukemic model and inoculated MLL-AF9 leukemia cells into WT or ST2−/− mice and additionally depleted Treg cells with anti-CD25 antibody (Clone No.: PC61) on day 1 and day 7 at the total dose of 500 μg/mouse or used isotype-Ab control (Rat IgG1) (Fig. 4G).