Increased prostaglandins E2 and F2alpha in human skin at 6 and 24 h after ultraviolet B irradiation (290− 320 nm).

I Abdominal skin of 25 human subjects was irradiated with three times its minimal erythema dose of ultraviolet (u.v.) B radiation. Erythema appeared after 2 h, was of moderate degree at 6 h, and maximal at 24 and 48 h. 2 Exudate was recovered by a suction bulla technique from the subject's normal and erythematous skin either at 6, 24 or 48 h after irradiation. 3 Superfusion cascade bioassay of exudate showed increased prostaglandin (PG)-like activity, measured in PGE2 equivalents, at 6 and 24 h after irradiation. The maximum rise was at 24 h, coinciding with the peak of the erythema. However, prostaglandin concentrations were not significantly above that of controls at 48 h when the erythema was still maximal.