Determining the ontogenetic origin of tissue dendritic cells (DCs) from macrophages is difficult. In Cell, Reis e Sousa and colleagues describe the generation of mice bearing Clec9a–yellow fluorescent protein (YFP) alleles and use these mice to fate-map the progeny of YFP+ bone marrow cells. Clec9a encodes a C-type lectin receptor, also known as DNGR-1, which is highly expressed in bone marrow lineage-negative CD115+ pre-DCs. Adoptive transfer of these cells yields exclusively CD11c+ conventional DC cells, including CD11b+, CD103+ and CD8α+ subsets. Importantly, monocytes, neutrophils and alveolar macrophages and Langerhans cells lack YFP labeling in the Clec9a-YFP mice. These data support the notion that Langerhans cells are a macrophage subset rather than DC subset. These mice thus provide a useful model to study the functional roles of distinct DC populations as compared to macrophages.

Cell 154, 843–858 (2013)