Spleen and liver dendritic cells differ in their tolerogenic and cytokine induction potential.

Dendritic cells (DCs) play an important role in induction of cellular immune responses. It seems that DCs that reside in different organs may be distinct in their ability to induce immune responses. This study was done to address the differences between spleen and liver DCs in induction of immune response and/or tolerance. CD11c+ DCs were separated from the liver and spleen of C57BL/6 mice and pulsed with myelin oligodendrocyte glycoprotein (MOG) peptide 35-55. 6105 MOG35-55 pulsed spleen or liver DCs were injected in foot pad of different groups of mice. Control groups received unpulsed DCs. After 5 days, the mononuclear cells (MNCs) of the regional lymph nodes were isolated from immunized mice for cytokine assays and lymphocyte transformation test. To study the immunologic or tolerogenic effects of DCs, three weeks after immunization of mice with MOG pulsed liver or spleen DCs, experimental autoimmune encephalomyelitis (EAE) was induced in DC-immunized mice by injection of MOG along with complete Freund's adjuvant. Our results showed that spleen DCs were more potent in stimulating lymph node T cells as illustrated in lymphocyte transformation test. Moreover IL-10 production was higher in mice immunized with liver DCs compared with those immunized with splenic DCs (p=0.017). However, no significant difference in IFN-γ production was observed between two groups. We also found that liver DCs+MOG immunized mice displayed a significantly delayed disease onset compared with spleen DCs+MOG immunized mice and the control groups. The disease score was also milder in liver DCs immunized mice compared with other groups. It seems that the higher IL-10 production induced by the liver DCs may be one of the main factors in down regulation of immune responses in this organ. It can be concluded also that the liver DCs may inhibit the progress of EAE by shifting the cytokines profile.