IL15 and leukemia: In addition, our data (35) demonstrated that the application of IL-15 instead of IL-2 during the generation of CIK cells in vitro downregulated the production of Tregs and IL-35, but resulted in a significant enhancement of CIK cell-mediated cytotoxicity against leukemia cells, suggesting that IL-15 may improve the cytotoxicity of CIK cells by inhibiting the production of Tregs and IL-35 expression.