title: Antigen processing: the gateway to the immune response.
abstract: The T-lymphocyte response to an antigen is governed by the source of that antigen and the way in which it is processed. Before recognition by T lymphocytes, proteins must be degraded to peptides by antigen-presenting cells. The peptides are then presented on major histocompatibility complex (MHC) molecules for recognition by the T cells. Antigens arising outside the cell (e.g., bacteria) are phagocytosed and processed by the exogenous pathway for presentation on MHC class II molecules (e.g., DR) to CD4+ cells. Antigens derived from the cytoplasm (e.g., viral proteins) are processed by the endogenous pathway for presentation by MHC class I molecules (e.g., HLA-A, -B, -C) to CD8+ cells. The response to a hapten or drug is a function of the antigen processing pathway and is determined by its chemical properties. Antigen processing also governs the T-cell response to pathogens, vaccines, and autoimmune conditions.
authors.affiliation: Department of Dermatology, State University of New York at Stony Brook 11794-8165.
authors.forename: R S
authors.initials: RS
authors.lastname: Kalish
mesh_terms: D017951:Antigen Presentation / Q000276:immunology*; D000938:Antigen-Presenting Cells / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D006680:HLA Antigens / Q000276:immunology; D006801:Humans; D010587:Phagocytosis / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology
chemical_list: D006680:HLA Antigens