EPIDERMAL STRATIFICATION REDUCES THE EFFECTS OF UVB (BUT NOT UVA) ON KERATINOCYTE CYTOKINE PRODUCTION AND CYTOTOXICITY.

Ultraviolet (UV) radiation induced cytokine release from cultured keratinocytes as well as from epidermis in vivo. The purpose of this study was to determine whether differentiation of cultured keratinocytes into stratified epithelium decreases the effects of UVA and UVB radiation on cytokine release. Interleukin-1 IL-1á, IL-1â and tumor necrosis factor (TNF)-á release from human keratinocytes and reconstituted human epidermis was measured after exposure to UVA and UVB radiation. Release of IL-1á, IL-1â and (TNF)-á was induced by both UVA and UVB radiation from both keratinocytes and reconstituted epidermis. Release of these cytokines was correlated with cytotoxicity. Keratinocyte cultures were far more sensitive to UVB radiation than reconstituted epidermis, in terms of both cytotoxicity and cytokine release. In contrast, epidermal stratification/defferentiation had much less effect on the sensitivity to UVA radiation. We conclude that epidermal stratification and the formation of a stratum corneum provide protection against UVB radiation but have limited barrier effect against UVA radiation.

Barrier effect, Cutaneous malignancies, Cytokines, Cytotoxicity, EpiDerm, Glucocorticoids, Hydrocortisone, IL-1a, IL-1b, Interleukin (IL), LDH, Ozone, Phototoxicity, Skin cancer, Sun screens, Sunburn reaction, TNF-a, Tumor necrosis factor alpha, UV light, UVA, UVB, Ultra-violet radiation (UV)