RORγt + dendritic cells are a distinct lymphoid-derived lineage

How tolerogenic dendritic cell (DC) lineages are established to prevent inappropriate immune responses to commensals and food antigens remains unclear. We identified RORγt + DCs in mice as a distinct lymphoid-derived lineage to safeguard intestinal tolerance. Using lineage tracing and single-cell transcriptomics, we unveiled bone marrow–resident Rorc(t) + progenitors, which include a RORγt + innate lymphoid progenitor (RILP) that generates both ILC3s and RORγt + DCs, and a pre–RORγt + DC precursor committed exclusively to the RORγt + DC lineage. RORγt + DC development required the Rorc +7-kilobase enhancer, whose accessibility was regulated by the repressors REV-ERBα and REV-ERBβ, and depended on the transcription factors PRDM16 and PU.1 for lineage commitment. Loss of any of these regulators abrogated RORγt + DC differentiation, reduced peripheral regulatory T cell (T reg cell) induction, and skewed toward T helper 2 responses. Together, these findings define murine RORγt + DCs as a lymphoid-derived lineage whose enhancer- and transcription factor–driven development is essential for peripheral T reg cell–mediated immune homeostasis.