UV-B and the immune system. A review with special emphasis on T cell-mediated immunity.
ABSTRACT The immunosuppressive activity of ultraviolet light-B (UV-B) has become 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 are described and analyzed with respect to the mode of action. In summary, this review demonstrated that UV-B can alter T cell mediated immune responses by different pathways in which cytokines (e.g. TNF-alpha) and other soluble mediators (e.g. cis-urocanic acid) may play a role. Effects of UV-B on the location and morphology of different cells in the skin affect functionality of the immune system. Thus, UV-B may suppress local immunity against skin tumours and skin-associated infections as well as systemic immunity against non skin-associated infectious diseases and tumours.
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ABSTRACT: Two types of antigen-specific T cells are needed for the elicitation of contact hypersensitivity reactions. They act in an obligate sequence to mediate the early initiating and late effector phases of contact hypersensitivity, which are accompanied by skin-swelling responses at 2 and 24 h after challenge, respectively. The magnitude of the late ear swelling depends on that of the early swelling.We studied the influence of ultraviolet radiation on both phases of contact hypersensitivity to picrylchloride. Mice were exposed to subedemal doses of ultraviolet radiation on the shaved backs for four consecutive days. Four days later mice were sensitized on non-irradiated skin. Four days after sensitization mice were challenged on the ears, and swelling was measured 2, 4, and 24 h after challenge. The early and late phases of contact hypersensitivity were largely suppressed in ultraviolet-irradiated, actively sensitized mice. Transfer of immune lymphoid cells from donor mice that were sensitized 4 d earlier induced early and late components of contact hypersensitivity in naive recipients after challenge. Transfer of immune lymphoid cells from donors that were sensitized 1 d earlier only induced the early component of contact hypersensitivity. Ultraviolet irradiation of donor mice significantly reduced the capacity of the immune lymphoid cells to induce contact hypersensitivity. We show that lymphoid cells responsible for the early and late components of contact hypersensitivity are both affected.Keywords: ultraviolet radiation, CHS, mice, photoimmunologyJournal of Investigative Dermatology 05/1994; 102(6):923-927. DOI:10.1111/1523-1747.ep12384051 · 6.37 Impact Factor
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ABSTRACT: To assess the relationship between immune system and nevi, we studied two models of immunodeficiency caused by different mechanism, i.e., virus and drug. Our rationale was that if an excess of nevi was found in these two epidemiologic models, it could be concluded that the excess was due to immunodeficiency itself rather than its cause. One hundred ten renal transplant recipients (RTR) were compared with age-, sex-, and phenotype-matched controls. Eighty four HIV-positive patients were compared with similarly matched controls. Nevi < 5 mm (N < 5) or 5 mm (N 5) were counted in three sites representative of regularly, intermittently, and never sun-exposed sites. The number of N < 5 was higher in RTR (p < 0.001) and in HIV+ (p < 0.001) than in respective controls. N 5 were significantly higher only in RTR. These differences tended to be the same for all sites and persisted after adjustment for possible confounding factors. The incidence of atypical nevus was higher in RTR than in controls. Immunodeficiency seems to promote the occurrence of nevi. This supports the concept of immune surveillance of nevi and raises the questions of whether sun-induced immune suppression plays a role in the development of nevi. As nevi are risk markers for melanoma, a higher incidence of melanoma could be expected in immunocompromised patients.Keywords: melanoma, prevention, sun exposureJournal of Investigative Dermatology 10/1996; 107(5):694-697. DOI:10.1111/1523-1747.ep12365586 · 6.37 Impact Factor
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ABSTRACT: Abstract Aneurysmal subarachnoid hemorrhage (SAH) is a common condition treated by neurosurgeons. The inherent variability in the incidence and presentation of ruptured cerebral aneurysms has been investigated in association with seasonality, circadian rhythm, lunar cycle, and climate factors. We aimed to identify an association between solar activity (solar flux and sunspots) and the incidence of aneurysmal SAH, all of which appear to behave in periodic fashions over long time periods. The Nationwide Inpatient Sample (NIS) provided longitudinal, retrospective data on patients hospitalized with SAH in the United States, from 1988 to 2010, who underwent aneurysmal clipping or coiling. Solar activity and SAH incidence data were modeled with the cosinor methodology and a 10-year periodic cycle length. The NIS database contained 32,281 matching hospitalizations from 1988 to 2010. The acrophase (time point in the cycle of highest amplitude) for solar flux and for sunspots were coincident. The acrophase for aneurysmal SAH incidence was out of phase with solar activity determined by non-overlapping 95% confidence intervals (CIs). Aneurysmal SAH incidence peaks appear to be delayed behind solar activity peaks by 64 months (95% CI; 56-73 months) when using a modeled 10-year periodic cycle. Solar activity (solar flux and sunspots) appears to be associated with the incidence of aneurysmal SAH. As solar activity reaches a relative maximum, the incidence of aneurysmal SAH reaches a relative minimum. These observations may help identify future trends in aneurysmal SAH on a population basis. Key Words: Solar flux-Sunspots-Patterns-Nationwide Inpatient Sample-Cerebral aneurysm. Astrobiology 14, xxx-xxx.Astrobiology 06/2014; 14(7). DOI:10.1089/ast.2014.1138 · 2.51 Impact Factor