Regulatory T cells (Tregs) are potent immunosuppressive cells and essential for inducing immune tolerance. Recent studies
have reported that Tregs and Tregs related cytokines can inhibit the antitumor activity of cytokine-induced killer (CIK) cells,
but dendritic cells co-cultured CIK (DC-CIK) cells can be used for induction of a specific immune response by blocking of
Tregs and TGF-b, IL-10. As a novel identified cytokine, IL-35 is specially produced by Tregs and plays an essential role in
immune regulation. However, it remains unknown whether IL-35 roles in tumor immunotherapy mediated by CIK and DCCIK
cells. In this study, we cultured CIK and DC-CIK cells from the same healthy adult samples, and investigated their
phenotype, proliferation, cytotoxic activity against leukemia cell lines K562 and NB4 by FCM and CCK-8, measured IL-35,
TGF-b and IL-10 protein by ELISA, detected Foxp3, IL-35 and IL-35 receptor mRNA by Real-time PCR, respectively. We found
Tregs and IL-35 concomitantly expanded by a time-dependent way during the generation of CIK cells, but DC significantly
down-regulated the expression of them and simultaneously up-regulated the proliferation ability as well as cytotoxic
activity of CIK cells against leukemia cell lines. Therefore, our data suggested that DC decreased concomitant expanded
Tregs and Tregs related IL-35 in CIK cells and might contribute to improve their cytotoxicity against leukemia cells in vitro.