We have demonstrated that direct antigen sampling of bacteria by intestinal dendritic cells (DCs) is accompanied by a rapid migration of CD11c^{+}CX_{3}CR1^{+}MHCII^{+}CD8α-CD11b^{−} DCs into the intestinal lumen upon exposure to non-invasive ΔSPI1-Salmonella. Importantly, intraluminal DCs internalized Salmonella but were not able to cross the epithelium to return into tissue, thus showing that these DCs do not function as antigen-presenting cells and participate in the conventional regulation of immune responses to intestinal pathogens. Here we show that the presence of the chemokine receptor CX_{3}CR1, that plays a vital role in DC-mediated antigen sampling and clearance in the gut, is also instrumental for the transepithelial migration of DCs. The latter observation, along with the notion that CX_{3}CR1-deficient mice displayed higher susceptibility to Salmonella infection compared to wild-type mice raises the possibility that Salmonella-induced migration of “bacteria-capturing” DCs into the lumen may be an important mechanism of mucosal defence and clearance.
【저자키워드】 mucosal immunity, dendritic cell, Salmonella, Cell migration, antigen sampling, immune exclusion, mucosal clearance,