Antigen presentation at the inflammatory site.
The introduction of antigen into tissues can induce an inflammatory response initiated by antigen-specific T lymphocytes. Central to this process is the recognition of antigen by specific T cells that cannot respond to intact antigen directly, but rather recognize antigenic fragments in association with gene products of the major histocompatibility complex (MHC) displayed by an antigen-presenting cell. To present antigen effectively, a cell must internalize antigen, process it to the immunogenic moiety, present the antigen in the context of a MHC molecule, and deliver various antigen-nonspecific signals required for T-cell activation. At the initiation of an immune response, the cells with the capacity to perform all of these functions are limited to a few specialized cell types, including monocytes/macrophages, dendritic cells, B cells, and Langerhans cells. Once the immune response has been initiated, however, cytokines and other factors, released by activated cells at the inflammatory site, stimulate a variety of changes in various cell types that alter their capacity to function as antigen-presenting cells and facilitate antigen-induced T-cell activation. Therefore, as the immunologically mediated inflammatory response evolves, a variety of changes occur within the local environment that enhance and/or modulate the capacity of T cells to recognize and respond to the inciting antigen. The purpose of this review is to catalog the changes in the function of antigen-presenting cells at inflammatory sites that might alter the nature of the immune response.
Geppert
T D
TD
Department of Internal Medicine, Southwestern Medical School, Dallas, Texas.
Lipsky
P E
PE
D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology / Q000502:physiology*; D000941:Antigens / Q000276:immunology*; D002450:Cell Communication; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D006801:Humans; D007249:Inflammation / Q000276:immunology*; D008213:Lymphocyte Activation; D013601:T-Lymphocytes / Q000276:immunology
D000941:Antigens; D015395:Histocompatibility Antigens Class I; D000949:Histocompatibility Antigens Class II