CTLA4 and leukemia: This observation is consistent with previous reports that MAIT and γδ T cells act as a first line of defense, and they possess the potential to kill leukemia cells.[20] Treg cells were characterized by high expression of the Treg signature genes Foxp3, IKZF2, IL2RA, and CTLA4 as well as co‐stimulatory markers, including CD28 and ICOS.