title: Ultraviolet-B radiation suppresses mast cell degranulation induced by compound 48/80.
abstract: This study was designed to investigate the effect of middle-wave ultraviolet (UVB) radiation on mast cell functions using mouse ear skin as an in vivo model. Groups of UVB-irradiated BALB/c mice were given an intradermal injection of the mast cell degranulator compound 48/80 into ears at various time intervals (30 min-7 days) after a single exposure to a bank of fluorescent sunlamp tubes (10-100 mJ/cm2). Both the compound-evoked ear swelling response (ESR) and mast cell degranulation were significantly suppressed by preexposure to UVB (25-100 mJ/cm2) after 0 (30 min) to 3 days postirradiation, with a subsequent recovery by day 7. No such effects were observed in mice irradiated with 10 mJ/cm2. The ESR induced by 5-hydroxytryptamine was not significantly affected by UVB radiation during the experimental period. While within this dose range UV radiation itself caused neither loss of mast cell counts nor a measurable degree of degranulation in ear skin, exposure to larger amounts of UV energy (200-500 mJ/cm2) produced tremendous ear swelling with histologic features of mast cell degranulation in an early phase of inflammation. The results suggest that UVB radiation exerts a dual effect on mast cells and that administration of smaller amounts of UVB may alter the mast cell/vasoactive amine system, suppressing ear swelling in response to the degranulator. Vascular reactivities to vasoactive amines were not affected by UVB irradiation.
mesh_terms: D000818:Animals; D004307:Dose-Response Relationship, Radiation; D004427:Ear Diseases / Q000139:chemically induced / Q000209:etiology; D004487:Edema / Q000139:chemically induced / Q000209:etiology; D005260:Female; D006097:Granulation Tissue / Q000166:cytology / Q000187:drug effects / Q000528:radiation effects*; D008407:Mast Cells / Q000000981:diagnostic imaging* / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D011833:Radiation Injuries, Experimental; D011877:Radionuclide Imaging; D012701:Serotonin; D014466:Ultraviolet Rays; D003189:p-Methoxy-N-methylphenethylamine / Q000494:pharmacology*
chemical_list: D012701:Serotonin; D003189:p-Methoxy-N-methylphenethylamine