Antigen-specific inhibition of experimental autoimmune uveoretinitis by bone marrow-derived immature dendritic cells

To investigate the effect of maturation status of bone marrow-derived dendritic cells (BMDCs) on the in vivo immune response to interphotoreceptor retinoid-binding protein (IRBP) 161-180 peptide in experimental autoimmune uveoretinitis (EAU).

Immature and mature BMDCs were generated without or with the stimulation by lipopolysaccharide (LPS), and their mRNA cytokine profile and phenotype were analyzed by RNase protection assay and flow cytometry. The effect of immature and mature DCs in inducing antigen-specific T-cell proliferation and cytokine profile was further investigated in an IRBP peptide-induced model of EAU.

BMDCs generated in granulocyte-macrophage-colony-stimulating factor (GM-CSF) were relatively immature (i)DCs, as determined by flow cytometry and cytokine profile. However, stimulation with LPS induced these cells to become mature (m)DCs with higher levels of surface major histocompatibility complex (MHC)-II and costimulatory molecules and higher mRNA expression of IL-1alpha, -1beta, -6, and -12. Subcutaneous administration of iDCs induced a state of relative tolerance to the peptide induced-EAU, and the effect was lost after the DCs underwent maturation induced by in vitro exposure to LPS. In vitro, both iDCs and mDCs induced typical peptide-specific T-cell proliferation, but IFN-gamma production by uveitogenic T cells was markedly inhibited by iDCs. In vivo, peptide-loaded iDCs induced draining lymph node (DLN) cells to secrete a distinct pattern of cytokine: namely, increased IL-10 and IL-5 and decreased IFN-gamma and IL-2, indicating an altered immune responses to a low T-helper (Th) cell type 1 profile and a high Th2 profile after uveitogenic challenge.

The data suggest that induction of tolerance to an autoantigen by peptide-loaded DCs requires presentation of antigen by iDCs and involves the generation of a high-level IL-10 and IL-5 immune response in DLN cells.