UV-A irradiation induces transcription of IL-6 and TNF alpha genes in human keratinocytes and dermal fibroblasts

Objective. To determine whether UV-A irradiation induces synthesis of infla mmatory cytokines in the skin. Methods. Human keratinocytes and dermal fibr oblasts were cultured and exposed to various doses of UV-A radiation. The c ellular distribution of IL-6 and TNF alpha was determined by indirect immun ofluorescence and by Bow cytometry with monoclonal anti-IL-6 and anti-TNF a lpha antibodies. Cytokine production was measured in the supernatants using an ELISA. IL-6 and TNF alpha transcription induced by W-A was determined b y reverse transcriptase-polymerase chain reaction (RT-PCR) amplification. R esults. IL-6 and TNF alpha were detected in small amounts in nonUV-A-irradi ated cell. W-A exposure was followed by significant increases in IL-6 and T NF alpha expression and by small increases in IL-6 and TNF alpha. levels in culture supernatants. RT-PCR demonstrated a UV-A-mediated increase in the transcription of IG 6 and TNF alpha genes. Conclusion. Synthesis of IL-6 an d TNF alpha can be induced by UV-A irradiation, This effect of W-A may cont ribute to the inflammatory skin changes seen during lupus flare-ups after s un exposure.