IL15 and graft versus host disease: In addition, a recent study showed that CD19-CAR T cells secreting IL-15/IL-15Rα complex are less toxic and express lower cytokines (such as IFN-γ), which is related to GvHD, than CD19-CAR T cells that express IL-15; in animal experiments, CD19-CAR T secreting IL-15/IL-15Rα complex can more effectively inhibit tumor growth than CD19-CAR T secreting IL-15; however, liver damage of IL-15/IL-15Rα-CD19-CAR T to mice is greatly reduced, and the score of GvHD is almost 0 (42).