ALPHA-MSH REGULATES INTERLEUKIN-10 EXPRESSION BY HUMAN KERATINOCYTES

Normal human keratinocytes (HKC) are able to synthesize alpha-MSH. Bec ause the production of alpha-MSH by HKC is induced significantly by ul traviolet B radiation, the involvement of keratinocyte-derived alpha-M SH in UV-induced immunosuppression has been suggested. The induction o f the antiinflammatory cytokine IL-10 in monocytes is a major mechanis m in the antiinflammatory actions of alpha-MSH. In the present study, HKC were investigated for their ability to produce IL-10 after alpha-M SH stimulation. HKC were obtained from the skin of human female breast sections and either left untreated or treated with 0.01 or 0.1 mu g/m l alpha-MSH for different times. Using RT-PCR, HKC were shown to expre ss IL-10 mRNA even under basal conditions, and treatment with alpha-MS H increased expression. Only minimal concentrations of IL-10 protein w ere detected in supernatants from the alpha-MSH-stimulated cultures. T o the best of our knowledge this is the first report of IL-10 expressi on by cultured HKC after alpha-MSH stimulation. Further studies are ne eded to determine the biological and therapeutic relevance of these fi ndings.