title: Abrogation of epidermal antigen-presenting cell function by ultraviolet radiation administered in vivo.
abstract: The exposure of animals to ultraviolet radiation (UVR) can result in dramatic alterations to their immunologic potential. Loss of ability to be contact-sensitized to skin-reactive chemicals applied to UVR-exposed surfaces, and an enhanced susceptibility to tumors induced by UVR represent two well-documented effects of such exposure. The skin Langerhans' cell (LC) is a cell type, having antigen presentation capabilities, which is functionally inactivated by UVR. The localized loss in the ability to induce a contact hypersensitivity (CS) response and the early events associated with the acquisition of a tumor-susceptible state have been hypothesized to involve LC inactivation by UVR. In this report we have investigated the relationship between the UVR-mediated loss of CS responsiveness and antigen-presenting cell (APC) function by LC following in vivo exposure of animals to UVR. The UVR-mediated loss of CS responsiveness was found to be both time-dependent and dosage-dependent, but the loss of epidermal APC function following the UVR exposure of dissociated epidermal cells or skin was immediate and dosage-dependent. The lack of time dependency associated with the loss of epidermal APC function may be due to the nature of the assay system being employed. Add-back experiments, using the proliferation of purified antigen-primed T-cells as a read-out system to evaluate APC function, require that the accessory cell be totally functional. Initiation of CS responses may still be possible, however, with LC that are partially UVR-inactivated. Lymph-node-associated and circulating accessory cells could be integrated into the response, providing any necessary components that the UV-inactivated LC lacks. We tested this possibility and conclude from these studies that this is indeed a viable possibility. Our results, therefore, provide a possible explanation for apparent differences in LC UVR susceptibility observed when in vitro and in vivo assays are employed.
mesh_terms: D000818:Animals; D000941:Antigens / Q000276:immunology / Q000528:radiation effects*; D003877:Dermatitis, Contact / Q000276:immunology*; D004139:Dinitrofluorobenzene / Q000008:administration & dosage / Q000276:immunology; D004307:Dose-Response Relationship, Radiation; D007801:Langerhans Cells / Q000276:immunology / Q000528:radiation effects*; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008213:Lymphocyte Activation; D051379:Mice; D008809:Mice, Inbred C3H; D013997:Time Factors; D014466:Ultraviolet Rays / Q000009:adverse effects*
chemical_list: D000941:Antigens; D004139:Dinitrofluorobenzene