title: No adaptation to UV-induced immunosuppression and DNA damage following exposure of mice to chronic UV-exposure.
abstract: It is well known that ultraviolet (UV) radiation induces erythema, immunosuppression and carcinogenesis. We hypothesized that chronic exposure to solar UV radiation induces adaptation that eventually prevents the suppression of acquired immunity. We studied adaptation for UV-induced immunosuppression after chronic exposure of mice to a suberythemal dose of solar simulated radiation (SSR) with Cleo Natural lamps, and subsequent exposure to an immunosuppressive dose of solar or UVB radiation (TL12). After UV dosing, the mice were sensitized and challenged with either diphenylcyclopropenone (DPCP) or picryl chloride (PCl). To assess the adaptation induced by solar simulated radiation, we measured the proliferative response and cytokine production of skin-draining lymph node cells after immunization to DPCP, the contact hypersensitivity (CHS) response to PCl, and thymine-thymine (T-T) cyclobutane dimers in the skin of mice. After induction of immunosuppression by SSR or by TL12 lamps, the proliferative response of draining lymph node cells after challenge with DPCP, or the CHS after challenge with PCl, showed significant suppression of the immune response. Chronic irradiation from SSR preceding the immunosuppressive dose of UV failed to restore the suppressed immune response. Reduced lipopolysaccharide-triggered cytokine production (of IL-12p40, IFN-gamma, IL-6 and TNF-alpha) by draining lymph node cells of mice sensitized and challenged with DPCP indicated that no adaptation is induced. In addition, the mice were not protected from T-T dimer DNA damage after chronic solar irradiation. Our studies reveal no evidence that chronic exposure to low doses of SSR induces adaptation to UV-induced suppression of acquired immunity.
authors.affiliation: Laboratory for Toxicology, Pathology and Genetics, National Institute for Public Health and the Environment, P.O. Box 1, 3720 BA Bilthoven, The Netherlands.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Steerenberg
authors.forename: Frieda
authors.initials: F
authors.lastname: Daamen
authors.forename: Eefke
authors.initials: E
authors.lastname: Weesendorp
authors.forename: Henk
authors.initials: H
authors.lastname: Van Loveren
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects*; D000818:Animals; D049109:Cell Proliferation / Q000528:radiation effects; D003521:Cyclopropanes / Q000276:immunology; D016207:Cytokines / Q000378:metabolism; D004249:DNA Damage; D003877:Dermatitis, Contact / Q000276:immunology; D004307:Dose-Response Relationship, Radiation; D007165:Immunosuppression Therapy; D008213:Lymphocyte Activation / Q000528:radiation effects; D051379:Mice; D008807:Mice, Inbred BALB C; D011836:Radiation Tolerance / Q000276:immunology*; D012867:Skin / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D013472:Sunlight; D013997:Time Factors; D014466:Ultraviolet Rays
chemical_list: D003521:Cyclopropanes; D016207:Cytokines; C029402:diphenylcyclopropenone