In addition to IL-17 production for host defense against tumors, MAIT cells are able to directly eliminate tumor cells through the expression of perforin and granzyme B after activation through their TCRs, which are specific against target tumor cells expressing MR1 in complex with metabolite antigens in the plasma membrane [7,8,9,10,11,12,13,14,28,30,31,41,47]. Here, MR1 is linked to neoplasm.