The role of dendritic cells during infection.

The skin and the mucosa of the respiratory and gastrointestinal tracts are continuously exposed to microorganisms, but only a limited number of these enter the body and cause disease. To resist microbial infection, the host has developed a multitude of defense mechanisms involving the innate and adaptive immune systems. Dendritic cells (DCs) provide the link between these arms of the immune system. The initiation of an immune response is critically dependent on the activation of DCs, which can discriminate between different classes of microorganisms and elicit tailored antimicrobial immune responses. They have an extraordinary capacity to stimulate naive T cells and initiate primary immune responses. In turn, some pathogens interfere with DC function to block or delay their elimination by the host. Progress in understanding the role of DCs in the host response to microbes is reviewed.