Classical dendritic cells are required for dietary antigen-mediated peripheral regulatory T cell and tolerance induction II

Oral tolerance prevents pathological inflammatory responses towards innocuous foreign antigens via peripheral regulatory T cells (pTreg cells). However, whether a particular subset of antigen-presenting cells (APCs) is required during dietary antigen exposure to instruct naïve CD4+ T cells to differentiate into pTreg cells has not been defined. Using myeloid lineage-specific APC depletion in mice, we found that monocyte-derived APCs are dispensable, while classical dendritic cells (cDCs) are critical for pTreg cell induction and oral tolerance. CD11b¬– cDCs from the gut-draining lymph nodes efficiently induced pTreg cells, and conversely, loss of IRF8-dependent CD11b– cDCs impaired their polarization, although oral tolerance remained intact. These data reveal the hierarchy of cDC subsets in pTreg cell induction and their redundancy during oral tolerance development. Sorted naïve CD45.1 OT-II CD4 T cells were co-cultured with four dendritic cell subpopulations sorted from mouse mesenteric lymphnodes. 24h later OT-II cells were sorted again and compared in their gene expression profile.