Growing up in vivo

摘要

Researchers define for the first time the stages of dendritic cell (DC) development in vivo and determine the site and time point at which DC and monocyte developmental pathways diverge. Monocytes and lymphoid tissue DCs of various subsets arise from a common progenitor known as the macrophage and DC precursor (MDP) in the bone marrow. To become a classical splenic DC (cDC), development is then thought to proceed via a common DC precursor (CDP), which is restricted to producing cDCs and plasmacytoid DCs (pDCs), and a dedicated cDC precursor (pre-cDC), which differentiates into cDCs in lymphoid organs. In keeping with this scheme, MDPs and CDPs could be detected in mouse bone marrow but not the blood and spleen, and pre-cDCs were found in all these sites, as well as the lymph nodes. Adoptive transfer of pre-cDCs confirmed their propensity to become cDCs. Experiments with parabiotic mice (which are surgically joined so that they share a blood circulation) led the authors to conclude that pre-cDCs arise in the bone marrow, travel through the blood to peripheral lymphoid organs, where they become cDCs.