FAS and neoplasm: In these groups, we found that NKT cells killed tumor cells in three ways and thus played an important anti-tumor role (1): in the Fas/FasL, perforin, and granzyme B pathways, they played a cytotoxic role and directly kill tumor cells (36) (2); they regulate the recruitment and function of other immune cells by secreting cytokines, thus indirectly playing an anti-tumor role (37) (3); NKT cells changed the immunosuppression level in the immune microenvironment, which resulted in anti-tumor activities (38).