Induction of Specific T-Cell Response Following In Vivo Treatment of Dendritic Cells by, 25-Dihydroxycholecalciferol

Dendritic cells (DCs), as the managers of the immune response, have a crucial role in forming the direction and nature of the immune response. Some compounds such as 1,25-dihydroxycholecalciferol affect the function of DCs and can be used to shift the immune functions toward favorite directions. The aim of this study was to investigate the in vivo effects of 1, 25- dihydroxycholecalciferol on DCs surface markers, their potential to induce specific T-cell responses and the cytokines profile. 1, 25-dihidroxycholecolciferol was regularly injected intraperitoneal into C57BL/6 mice. DCs were separated from the spleens of calciferol treated and non-treated mice using magnetic beads. The expression of DCs surface markers was investigated by flow cytometric analysis. The separated cells were pulsed by myelin oligodendrocyte glycoprotein (MOG) and injected subcutaneously into front footpads of syngeneic mice. After five days, the lymphocytes from regional lymph nodes were separated and used for the lymphocyte transformation test (LTT) and determination of the interferon gamma/interleukin 4 (IFNγ/IL-4) ratio by ELISA technique. Statistical analysis of the obtained results showed reduced expression ofmaturation markers and co-stimulatory molecules by cholecalciferol treated DCs. Thespecific T-cell stimulation potential of treated DCs as well as the induced IFNγ/IL-4 ratiowas also down-regulated compared to non-treated cells (p value<0.05). It seems that 1,25-dihydroxycholecolciferol can regulate the DCs function and maturation state in vivo. The T-cell stimulation rate and Th1/Th2 cytokines ratio also changes following interaction with cholecalciferol treated DCs.