Changes in the immune system of female sunbathers due to the effect of natural UV radiation.

Exposure to UV radiation may cause health hazards and suppress immune responses. The aim of this study was to evaluate whether recurrent suberythemal doses of natural UV radiation can have a harmful effect on the lymphocyte subpopulations of local sunbathers. Sixteen healthy local female volunteers at the age of 23 to 44 recurrently sunbathed during the summer of 2000 in the Pärnu beach area (58 degrees 22'N, 24 degrees 31'E). They were informed of the actual UV index and encouraged to gather only suberythemal UV doses. Before and after the sunbathing period the CD3+, CD3+CD4+, CD3+CD8+, CD19+, CD3-CD16+ CD56+, CD4+CD25+, CD4+HLA-DR+ and CD3+HLA-DR+ cells were determined in the peripheral blood of the volunteers. A statistically significant increase in the CD4+CD25+ and CD3+HLA-DR+ cells and a decrease in the CD3-CD16+CD56+ cells were detected. However, all changes remained in the normal range and there were no serious deviations in the composition of lymphocyte subpopulations. It was concluded that suberythemal doses of UV radiation gathered by volunteers had apparently no harmful effect on the immune system.