Effect of ultraviolet A on IL-1 production by ultraviolet B in cultured human keratinocytes.

ABSTRACT

Human skin is exposed to significant amounts of UVA and UVB radiation simultaneously. The effects of UVA and UVB interactions have been examined in many aspects such as erythema response. The effects of UVA on the production of cytokines by UVB have not been studied yet. The purpose of this study is to observe the effect of UVB and UVA on the production of IL-1 in cultured human keratinocytes and to determine whether UVA can modify the effects of UVB on the IL-1 production. Human keratinocytes derived from normal foreskin were exposed to UVA (0-30 J/cm2) and subsequently to UVB (0-50 mJ/cm2). After 48 h incubation, IL-1 levels in the culture supernatants and cell extracts of the cultured keratinocytes were measured by thymocyte proliferation assay. We have observed that UVB increased the production of IL-1 in cultured keratinocytes. However, UVA suppressed the production of IL-1 and also the stimulatory effect of UVB on the IL-1 production. We think that the opposite effects of UVB and UVA on the IL-1 production in human keratinocytes might explain the different action mechanisms of UVB and UVA in many cutaneous responses.