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Giornale Italiano di Dermatologia e Venereologia 2000 February;135(1):7-11


language: Italian

Evaluation of lymphocyte subsets and cutaneous urocanic acid in healthy volunteers after acute and chronic exposure to solar radiation.

De Simone C., Guerriero C., Masini C., Siani A. M. *, Norval M. **, Cerimele D.

Università Cattolica «S. Cuore» - Roma Istituto di Clinica Dermatologica * Università degli Studi «La Sapienza» - Roma Istituto di Fisica ** University of Edinburgh Department Medical Microbiology


Background. The ability of UVB radiation to impair the immunesurveillance against UV induced cancers has been well documented in experimental models, and the urocanic acid indicated as one of the mediators of this action. This study evaluates the modifications of lymphocyte subsets in the peripheral blood and urocanic acid isomers in the skin of human beings after exposure to solar radiation.
Methods. Blood samples have been obtained from 13 healthy volunteers before, immediately after and 7 days after a 1 hour-sun exposure. UCA samples have been taken from photoexposed and non-photoexposed skin at the same time. The same immunologic parameters have been evaluated in 15 subjects in January, in June (after the first exposures to the sun) and in September.
Results. The number of CD56+ cells decreased after acute exposure, while a highly significant increase in the percentage of cis-UCA has been demonstrated both in photoexposed and non-exposed areas. A significant reduction of CD3+ and CD4+ cells has been observed in June; CD56+ cells were increased in September. Total UCA content decreased in June and increased in September, to reach the maximum value in March, both in the photoexposed and non-photoexposed areas. The percentage of cis-UCA showed the minimum values in March, increased in June and decreased again towards the baseline in September, with a higher percentage in exposed than in unexposed areas.
Conclusions, Significant seasonal and acute modifications have been found in some immunological parameters, such as UCA isomers and lymphocyte subsets involved in T-cell mediated immune responses, that have been previously suggested as possible mediators of UV induced immunosuppression.

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