UV-INDUCED CUTANEOUS PHOTOBIOLOGY

Ultraviolet radiation (UVR) present in sunlight is a major environment al factor capable of affecting human health and wellbeing. The organ p rimarily affected by UVR is the skin, which is composed of a variety o f different cell types. Here, UVR is needed for production of active v itamin D as well as producing undesirable effects such as sunburn, pre mature cutaneous photoaging, and promoting skin cancer development. De pending on the radiation dose, UVR influences virtually every cutaneou s cell type investigated differently. Since the end of the nineteenth century, sun exposure has been known to induce skin cancer, which is n ow the human malignancy with the most rapidly increasing incidence. In several experimental models, mid-range UVR has been demonstrated to b e the major cause of UV-induced cutaneous tumors. The stratospheric oz one layer protecting the terrestrial surface from higher quantum energ y solar radiation is being damaged by industrial activities resulting in the possibility of increased UVR exposure in the future. Investigat ions in the field of experimental dermatology have shown that within t he skin an immunosurveillance system exists that may be able to detect incipient neoplasms and to elicit a host responses against it. This a rticle reviews the literature on studies designed to investigate the e ffects of UVR on cutaneous cellular components, with special focus on the immune system within the skin and the development of UV-induced ca ncer.