Ontogenetic Diversification of Type 2 Conventional Dendritic Cells in the Bone Marrow: A Central Logic for Peripheral Immunity.

Type 2 conventional dendritic cells (cDC2s) are central orchestrators of adaptive immunity. While historically considered a single population shaped by local microenvironments, recent evidence indicates that cDC2s comprise developmentally distinct subsets-cDC2As and cDC2Bs-with divergent ontogeny, tissue distribution, and immune functions. This review synthesizes current advances in the identification, differentiation, and functional characterization of these cDC2 subsets, with a focus on data supporting an early bifurcation at the level of bone marrow progenitors. We highlight how transcription factors such as TCF4 (and RBPJ) and KLF4 delineate cDC2A and cDC2B fates, respectively, and how subset-specific localization within tissues may amplify their distinct roles in immunity. We propose that early cDC2 diversification reflects a broader principle of central immune preconfiguration, in which the bone marrow senses peripheral immunological states and anticipates tissue-specific demands through progenitor programming. This hypothetical model redefines cDC2s not merely as adaptable responders to local cues, but as a paradigm for how immune output can be systemically preconfigured. As such, they offer a powerful lens through which to study how development and function intersect across immunity. Recent findings suggest that the ontogenetic logic in mouse cDC2 development may extend to humans, offering meaningful avenues for translational exploration.