Effects of solar radiation on the human immune system

On UV irradiation of the skin, a complex cascade of immunological changes r esults, initiated by cutaneous chromophores and ending in suppression of so me local and systemic immune responses. In this review, the stages in this process are outlined first, concentrating on the roles of DNA and urocanic acid as photoreceptors. Evidence indicating UV-induced immunomodulation of delayed hypersensitivity and resistance to infectious diseases in human sub jects follows. Aspects of genetic susceptibility to the immunosuppressive e ffects of UV exposure and extrapolation of the data obtained in animal mode ls to the human situation are included. Finally uncertain and unknown facto rs relating to the impact of UV on the human immune system are discussed. ( C) 2001 Elsevier Science B.V. All rights reserved.