Inflammatory reactions induced by ultraviolet irradiation

Exposure of human skin to short wavelength ultraviolet (U.V.) leads to increased concentrations of arachidonic acid and prostaglandins E2 and F2, but their role is uncertain. Although the levels of prostaglandins rise as erythema develops the correlation between intensity of erythema and prostaglandin activity is incomplete. There is mounting evidence that prostaglandins may regulate epidermal cell growth and differentiation through a cyclic-AMP dependent mechanism. The possibility therefore arises that prostaglandins, released in response to U. V. exposure, reduce proliferative activity in the exposed epidermis. This can be expected, in turn, to result in protection of skin from the mutagenic action of U. V. irradiation.