The Therapeutic Effects Of Dendritic Cells Synergistically Activated By Combined Toll-like Receptor Ligands Against CEA-expressing Colon Cancer In Vitro

Objective:To compare the immune functions of the dendritic cells (DCs) synergistically activated by combined Toll-like receptor (TLR) ligands and DCs generated in conventional way, as well as to compare the therapeutic effects of combined TLR activated DC cancer vaccine and conventional generated DC cancer vaccine against CEA-expressing colon cancer in vitro.Methods:Our study employs the CEA transgenic mice and CEA transfected MC38 mouse colon cancer cell line (MC38-CEA) as the animal model. We compare the celluar immune response-stimulating functions of combined TLR activated DCs and conventional generated DCs by testing the important surface molecules expression, IL-12 secretion and conducting the proliferation assays as well. Moreover, we pulse DCs with mouse MHC class I-restricted CEA epitope CEA_526-533 acting as CEA specific DC cancer vaccines and conduct the cytotoxicity assay to investigate their therapeutic effects against CEA-expressing colon cancer in vitro.Results:1 Combined TLR activated DCs' expression of important surface molecules is widely higher than conventional generated DCs'.2 Combined TLR activated DCs' secretion of IL-12 is significantly higher than conventional generated DCs' (P<0.001).3 The lymphocyte Proliferative response to combined TLR activated DCs is significantly higher than that to conventional generated DCs (P<0.05).4 The effector cells harvested from combined TLR activated DC cancer vaccine immunized mice show significant cytolytic activity against MC38-CEA cells at high E:T ratios (P<0.05), and there is no remarkable cytolytic activity observed in other groups. The effector cells harvested from both combined TLR activated and conventional generated DC cancer vaccine immunized mice show efficient cytolytic activity against CEA_526-533 pulsed MC38-CEA cells, and combined TLR activated DC group shows significant higher lysis at low E:T ratios (P<0.05).Conclusions:1 Compared with the conventional generated DCs, combined TLR activated DCs show better maturation status and can also stimulate celluar immune responses more effectively. This implicates its potential benefits in developing more powerful DC cancer vaccine.2 Combined TLR activated DC cancer vaccine can induce some CEA specific cytolytic activity against MC38-CEA cells in ex vivo cytotoxicity assay, however there is no remarkable cytolytic activity observed in conventional generated DC cancer vaccine immunized group. The therapeutic effects against MC38-CEA colon cancer cell line should be further studied through in vivo experiments.