Chronologic aging alters the response to ultraviolet-induced inflammation in human skin

In order to determine the effect of age on the capacity of human skin to mount an inflammatory response, the sunburn reaction was studied quantitatively in 4 subjects aged 22-26 yr and 7 subjects aged 62-86 yr. Buttock skin of each subject was exposed to 3 time his minimal erythema dose, using the Hanovia mercury vapor lamp; 1 micrometer histologic sections and determinations of histamine and prostaglandin E2 (PGE2) from suction blister aspirates were used to monitor the reaction. Clinically, erythema and edema were less (p less than .05) in irradiated skin of the old subjects during the first 24 hr. Nonirradiated skin contained less histamine and PGE2 in old adults (p less than .05), approximately 50% of young adult levels. Histamine levels rose early in the reaction and returned to baseline by 24 hr; 4 hr peak values averaged 9.2 ng/ml in old vs. 18.3 ng/ml in young adults. PGE2 rose more slowly in blister aspirates from old adults (P less than .05), but reached comparable peaks, 6-9 pg/T.V., in both groups at 24 hr. Biopsies of control skin from old adult specimens contained fewer mast cells and venules (P less than .01). At 4 and 24 hr, old specimens revealed fewer sunburn cells and less striking alterations of perivenular mast cells and endothelial cells, but at 72 hr these changes were more prominent than in young adult specimens. The data suggest that with advancing age the sunburn reaction is quantitatively reduced and evolves more slowly following a standardize ultraviolet exposure.