Induction of type II collagen-reactive IL-10-producing CD11b⁺ dendritic cells in Payer's patch of orally tolerized animals

To further understand the role of dendritic cells (DCs) in the immune tolerance mechanism, we examined the phenotypic distribution and cytokine profiles of DCs in Payer's patch, separate from an orally tolerized collagen-induced arthritis (CIA) model.

Oral tolerance was successfully generated at 5 weeks after first immunization with type II collagen (CII), showing that the joint inflammations were significantly subdued in the CIA mice model after six times repeated administration of soluble CII (100 μg) at 2 day intervals. The distribution of DC subtypes was evaluated by confocal microscopy, labeled with fluorescent-tagged antibodies of CD8α (lymphoid DC) and CD11b (myeloid DC) markers. The production and expression of IL-10 and IL-12 cytokines in each DC subsets were examined by FACS analysis and confocal microscopy.

In tolerized mice, CD11c(pan DC)⁺CD11b DCs were clearly present within the subepitherial dome region of Peyer's patch and CD11c⁺CD8α DCs were not significantly localized in the interfollicular region. These finding is quite comparable with normal controls or CIA animals.

When the DCs were cocultured with T cells for 3 days in the presence of CII, IL-10-producing CD11b⁺ DCs were increased and IL-12-producing DCs were decreased in tolerized mice. CD4⁺CD25⁺ T cells in Peyer's patch were also induced by consecutive CII stimulation in tolerized mice, not in control and CIA model mice. We found that the IL-10-producing DCs and CD4⁺CD25⁺ T cells in tolerized mice were successfully generated by in vitro culture with CII antigen stimulation. In conclusion, the data suggest that induction of antigen-specific myeloid DCs and CD4⁺CD25⁺ T cells in Peyer's patch plays a very important role in initiation of the oral tolerance mechanism.