title: Bivalent effect of UV light on human skin mast cells-low-level mediator release at baseline but potent suppression upon mast cell triggering.
abstract: Ultraviolet (UV) irradiation is an established treatment for inflammatory skin diseases, although the precise mode of action is still unclear. Activating and suppressive effects on mast cell (MC) mediator release have been described. The aim of this study was to investigate systematically the effects of UVB, UVA-1, and psoralen plus UVA-1 at therapeutic doses on skin-derived human MC. Baseline and stimulated release of histamine, tryptase, and of interleukin (IL)-6, IL-8 and tumor necrosis factor-alpha (TNF-alpha) were examined. In resting MC, UV light induced a slight, yet significant histamine release corresponding to enhanced surface levels of lysosome-associated membrane proteins (LAMP). In contrast, UV pre-treatment caused a marked suppression of the anti-IgE-induced histamine release, accompanied by a diminished, anti-IgE-mediated increase in LAMP expression. The secretion of IL-6, IL-8, and TNF-alpha was inhibited in resting and activated MC, suggesting a different mode of action. Regarding the importance of MC in a variety of allergic and inflammatory processes, our data show a high susceptibility of this cell type towards UV light, which seems to partially depend on the state of cellular activation. Immunosuppressive effects predominate in activated MC, thus corresponding with the beneficial effects in inflammatory diseases, whereas in resting MC, both stimulatory and inhibitory effects are observed.
authors.affiliation: Department of Dermatology and Allergy, Charité Campus Mitte, Schumannstr. 20/21, D-10117 Berlin, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Guhl
authors.forename: Richard
authors.initials: R
authors.lastname: Stefaniak
authors.forename: Marc
authors.initials: M
authors.lastname: Strathmann
authors.forename: Magda
authors.initials: M
authors.lastname: Babina
authors.forename: Helmut
authors.initials: H
authors.lastname: Piazena
authors.forename: Beate M
authors.initials: BM
authors.lastname: Henz
authors.forename: Torsten
authors.initials: T
authors.lastname: Zuberbier
mesh_terms: D016207:Cytokines / Q000378:metabolism; D005363:Ficusin / Q000494:pharmacology; D006636:Histamine Release / Q000528:radiation effects*; D006801:Humans; D007165:Immunosuppression Therapy; D066298:In Vitro Techniques; D008407:Mast Cells / Q000276:immunology / Q000378:metabolism / Q000528:radiation effects*; D017319:Photosensitizing Agents / Q000494:pharmacology; D014466:Ultraviolet Rays
chemical_list: D016207:Cytokines; D017319:Photosensitizing Agents; D005363:Ficusin