Cytotoxicity of CD19-CAR T cells was inhibited by metformin. (A) CD19-CAR T cells were cocultured with Raji and K562 cell lines at various E:T (1:1, 5:1, 10:1, 20:1, and 40:1) for 24 hours. The apoptotic rate was determined by flow cytometry. (B) CD19-CAR T cells were cocultured with Raji cell lines with 0, 1, and 10 mM metformin at various E:T (1:1, 5:1, 10:1, 20:1, and 40:1) for 24 hours. The apoptotic rate was determined by flow cytometry. (C) CD19-CAR T cells were cocultured with Raji cell lines with metformin (0, 1, 10, and 20 mM) at various E:T (1:1, 5:1, 10:1, 20:1, and 40:1) for 24 hours, and the supernatant was obtained from the cocultured system. The IL-2 secretion was detected by ELISA. (D) CD19-CAR T cells were cocultured with Raji cell lines with metformin (0, 1, 10, and 20 mM) at various E:T (1:1, 5:1, 10:1, 20:1, and 40:1) for 24 hours, and the supernatant was obtained from the cocultured system. INF-γ secretion were detected by ELISA. The bar graph represents the results of three independent experiments, *P<0.05, **P<0.01 versus the control group.
Abbreviations: CAR, chimeric antigen receptor; Met, metformin; IL, interleukin; INF, interferon; E:T, effector to target cell ratio.