title: Innate immune recognition.
abstract: The innate immune system is a universal and ancient form of host defense against infection. Innate immune recognition relies on a limited number of germline-encoded receptors. These receptors evolved to recognize conserved products of microbial metabolism produced by microbial pathogens, but not by the host. Recognition of these molecular structures allows the immune system to distinguish infectious nonself from noninfectious self. Toll-like receptors play a major role in pathogen recognition and initiation of inflammatory and immune responses. Stimulation of Toll-like receptors by microbial products leads to the activation of signaling pathways that result in the induction of antimicrobial genes and inflammatory cytokines. In addition, stimulation of Toll-like receptors triggers dendritic cell maturation and results in the induction of costimulatory molecules and increased antigen-presenting capacity. Thus, microbial recognition by Toll-like receptors helps to direct adaptive immune responses to antigens derived from microbial pathogens.
authors.affiliation: Section of Immunobiology and Howard Hughes Medical Institute, Yale University School of Medicine, New Haven, Connecticut 06520-8011, USA. charles.janeway@yale.edu
authors.forename: Charles A
authors.initials: CA
authors.lastname: Janeway
authors.forename: Ruslan
authors.initials: R
authors.lastname: Medzhitov
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001324:Autoantigens / Q000378:metabolism; D029721:Drosophila Proteins / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D007239:Infections / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface / Q000276:immunology; D011971:Receptors, Immunologic / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction; D051193:Toll-Like Receptors
chemical_list: D001324:Autoantigens; D029721:Drosophila Proteins; D008562:Membrane Glycoproteins; D011956:Receptors, Cell Surface; D011971:Receptors, Immunologic; C068721:Tl protein, Drosophila; D051193:Toll-Like Receptors