EFFECTS OF PETROCHEMICALS AND ULTRAVIOLET-RADIATION ON EPIDERMAL IA EXPRESSION INVITRO

We previously demonstrated that combined treatment of mice with crude oil and longwave ultraviolet radiation (UVA) led to the depletion of IA-positive cells from the epidermis. In the present study, we have developed an in vitro screening assay for combined effects of purified petrochemicals and UVA on epidermal IA and Thy-1 expression. This method involves removal of skin from donor mice prior to treatment with chemicals and UVA (20,000 J/m2), followed by in vitro culture and subsequent immunoperoxidase staining. In this study, a complete correlation was observed in terms of IA-positive cell density among similarly treated cultured skin and live mice. In vivo and in vitro studies both indicated that anthracene but not phenanthrene or benzo[a]pyrene led to significant depletion of both epidermal Langerhans cells and Thy-1-positive dendritic cells when followed by UVA treatment. The in vitro assay developed for this study should prove to be a valuable tool for the screening of a wide variety of chemicals for contact photosensitizing activity.