NERVE GROWTH-FACTOR LEVELS IN CULTURED HUMAN SKIN CELLS - EFFECT OF GESTATION AND VIRAL TRANSFORMATION

Extracts of cultured human keratinocytes and fibroblasts were assayed for nerve growth factor-like immunoreactivity (NGF) by a specific enzy me-linked immunoabsorbant assay. NGF levels were higher in primary cul tured keratinocytes than in freshly isolated keratinocytes or culture through multiple passages. Viral transformation of keratinocytes with the human papilloma virus (HPV16) significantly increased NGF levels, whilst transformation with the simian virus (SV40), which induces simp le epithelial differentiation, reduced the concentration of NGF. Passa ged epidermal keratinocytes contained more than twice as much NGF as d id passaged fibroblasts. Oral keratinocytes and fibroblasts, and psori atic fibroblasts, all from high turnover tissues, did not contain sign ificantly different levels of NGF in culture than dermal keratinocytes or fibroblasts. Foetal fibroblasts contained five times as much NGF a s did adult fibroblasts. These results suggest that basal keratinocyte s are a major but not sole source of NGF in human skin, and that NGF m ay play a role in human skin development.