Replicate in Bone Marrow-Derived CD11c Cells but Not in Dendritic Cells Isolated from the Murine Gastrointestinal Tract.

Recent fate-mapping studies and gene-expression profiles suggest that commonly used protocols to generate bone marrow-derived cultured dendritic cells yield a heterogeneous mixture, including some CD11c cells that may not have a bona fide counterpart in vivo. In this study, we provide further evidence of the discordance between ex vivo-isolated and in vitro-cultured CD11c cells by analyzing an additional phenotype, the ability to support cytosolic growth of the facultative intracellular bacterial pathogen Two days after foodborne infection of mice with GFP-expressing , a small percentage of CD103 and CD103 conventional dendritic cells (cDC) in the intestinal lamina propria and mesenteric lymph nodes were GFP However, in vitro infection of the same subsets of cells harvested from naive mice resulted in inefficient invasion by the bacteria (<0.1% of the inoculum). The few intracellular bacteria detected survived for only a few hours. In contrast, cultured CD103CD11c cells induced by GM-CSF readily supported exponential growth of Flt3 ligand-induced cultures yielded CD103CD11c cells that more closely resembled cDC, with only a modest level of replication. For both culture protocols, the longer the cells were maintained in vitro, the more readily they supported intracellular growth. The results of this study suggest that cDC are not a niche for intracellular growth of during intestinal infection of mice.