1113 T-Bet Mediated Anti-Neoplastic Effects of Dendritic Cell-Cytokine Induced Killer Cells In-Vitro

Abstract

Background and aims: To investigate the molecular mechanism underlying T-bet mediated anti-neoplastic effects of cytokine induced killer (CIK) cells.Methods: Lymphocytes isolated from peripheral blood of leukemic children were induced with IFN-γ, CD3McAb and IL-2 and co-cultured with dendritic cells (DCs) to generate DC-CIK cells. The morphology and immunophenotype of these cells were determined by electron microscopy and flow cytometry, respectively. IL-2 and IFN-γ levels released by DC-CIK cells were quantified by ELISA. Cytotoxicity of DC-CIK cells against leukemia cell lines was measured by the MTT assay. FCM was used to detect CD4+CD25+Treg cells, while RT-PCR and Western blot were used to determine mRNA and protein expressions of Foxp3 and GATA3 in DC-CIK cells treated with T-bet monoclonal antibody.Results: Induced DC-CIK cells were regular, round and transparent with variable cell volume and cellular aggregation. The main effector cells in this population were CD3+CD8+ cells and CD3+CD56+ cells. We demonstrated a time dependent increase in IL-2 and IFN-γ levels after induction. DC-CIK cells were cytotoxic to B95 cells, Jhhan cells and M07e cells, with the highest cytotoxicity towards B95 cells. Treatment with mouse anti-human T-bet monoclonal antibody resulted in an increase in the proportion of CD4+CD25+Treg cells and elevation of Foxp3 and GATA3 mRNA and protein levels.Conclusion: DC-CIK cells induced with cytokines were strongly cytotoxic towards a number of cancer cell lines. Foxp3 and GATA3 were implicated in the T-bet mediated anti-neoplastic effects of DCCIK cells via activation of the Th1 pathway and suppression of theTh2 and Treg pathways.