Remarkable elevation of leukotriene B4 in rat skin after induction of UV photodermatitis.

Leukotriene B4 in the skin was remarkably elevated in the rat, but not in the guinea pig or the mouse 48 h after UV-B irradiation. These results were consistent with interspecies difference of PMN infiltration caused by UV-B irradiation. LTB4 in the rat skin was determined by both high-performance liquid chromatography and radioimmunoassay. LTB4 in the rat skin started to increase 24 h after irradiation and became about 65-fold higher in the irradiated site than in the nonirradiated site at the end of 48 h. This elevation was strongly inhibited by topical application of two 5-lipoxygenase inhibitors, AA-861 and piriprost, although the inflammatory reaction or infiltration of polymorphonuclear leukocytes was not much improved.