Dendritic cells (DCs) associate the capacity to sense pathogens with the initiation of adaptive immunity. Pathogens can be sensed through pathogen-associated molecular patterns by pathogen-recognition receptors expressed on host cells. Pathogen-encoded activities can also be sensed when they modify normal host cellular processes. The diversity of pathogen sensors has been highlighted by the identification of several cytosolic sensors involved in the recognition of nucleic acids from pathogens. The number of these pathogen cytosolic sensors has dramatically increased recently. Different DC populations appear to be equipped with distinct sensors but the precise expression pattern and the regulation of these sensors remain to be established, especially in humans. The engagement of sensors in DCs by pathogens leads to antipathogen effects through multiple mechanisms including interferon responses and promotes effector pathways that can shape the adaptive immune response. How the diversity of cytosolic pathogen sensors impacts these processes is incompletely understood. Investigating the expression, regulation, and crosstalk of the sensors should shed light on how pathogen sensing impacts pathogen replication and host immune responses.
Keywords: Adaptive immunity; DC subsets; DNA sensors; Dendritic cells; HIV; Innate immunity; Pathogen sensors; RNA sensors; Type I interferon.
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