Taken together, the MR1/TCR-dependent pathway could mainly promote the development of MAIT cells and exert an anti-gut aGVHD effect, while IL-12/IL-18 and other cytokine signals mainly promote mature subsets to express more cytotoxic cytokines and exert an important graft-versus-leukemia (GVL) effect, thereby balancing the effects of anti-gut aGVHD and graft-versus-leukemia (GVL) to maintain immune homeostasis. Here, IL18 is linked to leukemia.