Lamina propria dendritic cells in the physiology and pathology of the gastrointestinal tract.

PURPOSE OF REVIEW: The mucosal immune system constantly surveys the intestinal microbiota. The outcome of this interaction is determined by the functional properties of dendritic cells, which play a key role in immune response by facilitating antigen sampling and pathogen recognition, as well as innate host defenses. RECENT
FINDINGS: Recent advances have provided insight into the diverse mechanisms involved in the acquisition of intestinal antigens and led to a new appreciation of organ-specific functional subspecification of dendritic cell subsets. Dendritic cells are not a rare cell type in the intestine but populate the entire lamina propria of the gastrointestinal tract as an extensive network. Distinct dendritic cell subsets may be associated with specific immune functions in the lamina propria and Peyer's patches. Newly discovered routes of antigen acquisition, such as the formation of transepithelial dendrites, allow dendritic cells direct access to the intestinal lumen to obtain information about commensal and pathogenic microorganisms. Dendritic cells emerge as key regulators of the intestinal immune system with their ability to direct intestine-specific migration and control of T cells.
SUMMARY: Dendritic cells play a major role in the complex interactions between the gut microbiota and the innate and adaptive immune system, leading to tolerance and immunity. Recent contributions have yielded important information that may aid in the development of novel therapeutic approaches to the treatment of inflammatory bowl disease and intestinal infections and to new immunization strategies.