Experimental autoimmune encephalomyelitis (EAE) induced by antigen pulsed dendritic cells in the C57BL/6 mouse: influence of injection route.

Dendritic cells (DCs) are the most potent antigen-presenting cells (APC) of the immune system, and are critically involved in initiation of immune responses in autoimmune diseases. They can modulate the nature of immune responses to stimulatory or tolerogenic fashion. Previous studies have demonstrated that the administration route of DCs is an important variable in eliciting anti-tumor immunity. In this study we used experimental autoimmune encephalomyelitis (EAE) as an animal model of multiple sclerosis to compare different protocols of DC delivery in autoimmunity or tolerance induction. Dendritic cells were generated from bone marrow cells of C57BL/6 mice by culturing in the presence of GM-CSF and IL-4 for 7 days, followed by 2 days culture with TNF-alpha. The obtained DCs were pulsed in vitro with myelin oligodendrocyte glycoprotein (MOG) peptide and injected (5 x 10(5) cells/mouse) via the intravenous (i.v.), intraperitoneal (i.p.) or subcutaneous (s.c.) route into female C57BL/6 mice. In some instances pertussis toxin was also injected zero and 48 hours after DC injection. After follow up of the mice pretreated in this way for 4 weeks, in the i.v. group in which no clinical signs of EAE occurred, the mice were immunized with MOG peptide for EAE induction via the common method and the results were compared with mice that were not pre-immunized. Only after three s.c. DC injections with pertussis toxin, the mice showed mild clinical signs of EAE, whereas mice given i.v. or i.p. injections with or without pertussis toxin failed to develop EAE after 4 weeks. Induction of EAE via the common method after three injections of TNF-alpha treated DCs, in i.v. injected groups showed no protection from EAE. It seems that several factors influence the tolerance versus immunity induction by DCs. Our results showed that the administration route of DCs is one of the pivotal factors in DC-based induction of autoimmune diseases.