title: [The epidermis as an immune organ].
abstract: The epidermis possesses everything required for initiation of an immune response. It harbors antigen-presenting Langerhans cells, it produces immune modulatory cytokines, and (so far shown only in the murine system) it contains a distinct T cell population. Both upregulating and downregulating signals, leading to either sensitization or tolerance, are generated in the epidermis after exposure to antigens, and both have distinct cellular origins. While sensitizing and tolerogenic signals are usually balanced in such a way that Langerhans cell-generated sensitization is predominant, a breakdown of Langerhans cell function results in suppressive mechanisms. The structural and antigenic similarity between epidermis and thymus, the secretion of cytokines by keratinocytes, the migration of lymphocytes into the epidermis and the heterogeneity of TCR expression on Thy-1+ dendritic epidermal cells residing in (murine) epidermis and cell lines derived thereof all suggest that the epidermis is a site of postthymic or extrathymic T cell maturation.
authors.affiliation: I. Universitäts-Hautklinik Wien.
authors.forename: K
authors.initials: K
authors.lastname: Wolff
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology; D000818:Animals; D000938:Antigen-Presenting Cells / Q000276:immunology; D001685:Biological Factors / Q000502:physiology; D016207:Cytokines; D003877:Dermatitis, Contact / Q000276:immunology; D006801:Humans; D007801:Langerhans Cells / Q000276:immunology; D012867:Skin / Q000276:immunology*; D014181:Transplantation Immunology
chemical_list: D001685:Biological Factors; D016207:Cytokines
vernacular_title: Immunorgan Epidermis.