Fig. 2

FLT3L CAR-T cells exhibited antigen-specific cytotoxicity against FLT3⁺ leukemia cells. a FLT3 expression in AML cell lines analyzed by flow cytometry after staining with anti-FLT3 antibody (black line); the corresponding isotype (gray line) is used as negative control. SFI of FLT3 expression was calculated by dividing the median fluorescence of FLT3 mAb staining by the median fluorescence of mouse IgG1 κ isotype control. b, c Percentage of CD3⁺CD107a⁺ T cells after being co-cultured with target cells for 5 h was determined by flow cytometry. d Cytotoxic activity of FLT3L CAR-T against FLT3-positive or FLT3-negative AML cell lines. Target cells and effector cells were co-cultured for 48 h at the indicated E:T ratio. Anti-CD33 or anti-CD19 antibody and anti-CD3 antibody were used to recognize different cell types. e CAR-T or VEC-T cells were co-cultured with leukemia cells for 24 h. IFN-γ, TNF-α, and IL-2 amounts in the supernatants were analyzed by using ELISA