UV-B AND THE IMMUNE-SYSTEM - A REVIEW WITH SPECIAL EMPHASIS ON T-CELL-MEDIATED IMMUNITY

The immunosuppressive activity of ultraviolet light-B (UV-B) has becom e a major topic of interest, especially now that there are indications of an increased exposure to UV-B on the earth's surface, caused by a decreased thickness of the ozone layer. This review indicates that the thymus-dependent immune system is a prime target for damage by UV-B. Especially the systemic effects of UV-B on T cell mediated immunity ar e described and analyzed with respect to the mode of action. In summar y, this review demonstrated that UV-B can alter T cell mediated immune responses by different pathways in which cytokines (e.g. TNF-alpha) a nd other soluble mediators (e.g. cis-urocanic acid) may play a role. E ffects of UV-B on the location and morphology of different cells in th e skin affect functionality of the immune system. Thus, UV-B may suppr ess local immunity against skin tumours and skin-associated infections as well as systemic immunity against non skin-associated infectious d iseases and tumours.