UVB irradiation induces lipid peroxidation and reduces antioxidant enzyme activities in human keratinocytes in vitro.

Exposure of human keratinocytes to UVB irradiation resulted in formation of conjugated double bonds and thiobarbituric acid reactive material. The activities of superoxide dismutase and catalase, enzymes which protect cells against oxidative damage, were concomitantly reduced. The present study suggests that in keratinocytes, exposure to UVB irradiation leads to a chain of events resulting in lipid peroxidation reactions accompanied by an impairment of the cellular defence system against reactive oxygen species. These phenomena may act synergistically in UVB-induced cutaneous pathological processes, such as carcinogenesis.