Influence of UV irradiation on the composition of human stratum corneum lipids.

Irradiation with suberythemal doses of either UV-A or UV-B yielded an increase in the amount of stratum corneum lipids extracted from the lumbar skin area of 20 volunteers. These lipids were quantified after separation by high-performance thin-layer chromatography. Ten subfractions in the ceramide region were separated; two of them (fractions 7a and 7b) were only detectable after UV-A or UV-B irradiation. Improvement of barrier function after UV irradiation of human skin with suberythemal doses may be related to an increase in the stratum corneum ceramides.