DENDRITIC CELL ONTOGENY - A HUMAN DENDRITIC CELL LINEAGE OF MYELOID ORIGIN

Dendritic cells (DC) have been thought to represent a family of closel y related cells with similar functions and developmental pathways, The best-characterized precursors are the epidermal Langerhans cells, whi ch migrate to lymphoid organs and become activated DC in response to i nflammatory stimuli, Here, we demonstrate that a large subset of DC in the T cell-dependent areas of human lymphoid organs are nonactivated cells and belong to a separate lineage that can be identified by high levels of the interleukin 3 receptor alpha chain (IL-3R alpha(hi)). Th e CD34(+)IL-3R alpha(hi) DC progenitors are of myeloid origin and are distinct from those that give rise to Langerhans cells in vitro, The l L-3R alpha(hi) DC furthermore appear to migrate to lymphoid organs ind ependently of inflammatory stimuli or foreign antigens. Thus, DC are h eterogeneous with regard to function and ontogeny.