Recent research found that scFv-based FLT3 CAR-T cells released significantly increased IL-2 and IFN-γ when co-cultured with target cells [11], while in our study, IL-2 was slightly increased when co-cultured with FLT3-ITD leukemia cells and nearly not changed when co-cultured with FLT3-WT leukemia cells. Here, IL2 is linked to leukemia.