Effect of ultraviolet radiation and PUVA on mediator release from purified mast cells.

Exposure of highly purified rat serosal mast cells to UVA (34-340 kJ/m2), in the presence or absence of 8-methoxypsoralen (100 ng/ml), or to UVB (160-640 J/m2), resulted in dose-dependent releases of mast cell preformed mediators, as measured by the release of radioactivity from 3H-serotonin-labeled cells. The net release ranged from 2.3% to 14.2%. The above treatments had no effect on mediator release induced by subsequent incubation with calcium ionophore A23187 (0.4 and 4.0 mumol/l) or with compound 48/80 (1.0 microgram/ml), with the exception that exposure to UVB did suppress the release induced by the latter. These results indicate that under clinically relevant conditions, the direct effect of in vitro ultraviolet radiation on mast cells did not alter the ability of these cells to respond to subsequent stimulation with secretagogues.