title: Modulation of human cutaneous mast cell responsiveness by a single, low-dose, PUVA treatment.
abstract: The present study was conducted to investigate whether a single administration of a relatively low dose of 8-methoxypsoralen (8-MP) with long-wave ultraviolet A (UVA) irradiation alters human skin test responses to a mast cell secretagogue, codeine, and to a vasodilator, histamine. Administration of 8-MP at a dose of 10 mg followed by UVA irradiation (1 joule/cm2) suppressed the skin flare-and-wheal response to codeine and decreased the number of visible degranulated mast cells in biopsy specimens examined histologically. UVA irradiation alone enhanced the skin wheal-and-flare response to either codeine or histamine. The inhibitory effect of 8-MP plus UVA irradiation on both wheal-and-flare responses to codeine tended to decrease, and an increasing enhancement of the skin response to histamine could be observed as the dose of 8-MP was increased from 10 to 30 mg. We postulate that (1) a single 8-MP plus UVA irradiation treatment at appropriate doses could be a potential approach to modulate the mediator-releasing properties of mast cells resident in the skin and (2) the underlying mechanisms of this inhibition is complex, probably reflecting a balance between the inhibitory effect of 8-MP plus UVA irradiation on mast cell-mediator release, enhancement of the vascular response to histamine, and direct photoactivation of resident mast cells.
authors.affiliation: Department of Medicine, University of California-San Diego School of Medicine 92103-1990.
authors.forename: A
authors.initials: A
authors.lastname: Yen
authors.forename: I
authors.initials: I
authors.lastname: Gigli
authors.forename: K E
authors.initials: KE
authors.lastname: Barrett
mesh_terms: D000328:Adult; D003061:Codeine; D004305:Dose-Response Relationship, Drug; D005260:Female; D006632:Histamine; D006801:Humans; D008297:Male; D008407:Mast Cells / Q000000981:diagnostic imaging / Q000187:drug effects / Q000276:immunology*; D008730:Methoxsalen / Q000494:pharmacology; D008875:Middle Aged; D011701:PUVA Therapy; D011859:Radiography; D012016:Reference Values; D012867:Skin / Q000000981:diagnostic imaging / Q000187:drug effects / Q000276:immunology*; D012882:Skin Tests; D014466:Ultraviolet Rays
chemical_list: D006632:Histamine; D008730:Methoxsalen; D003061:Codeine