REQUIREMENTS FOR LANGERHANS CELL DEPLETION FOLLOWING IN-VITRO EXPOSURE OF MURINE SKIN TO ULTRAVIOLET-B

Langerhans' cells found within the skin and mucous membranes are criti cal regulators of antimicrobial and allergic responses. Therefore, the depletion of these cells following exposure of skin to solar ultravio let radiation (UV) has direct functional consequences on immunity with in this tissue. In order to understand how Langerhans' cell depletion is regulated following exposure of skin to medium-wave UV (UVB), the r ole of second messengers in these responses was investigated using a n ovel in vitro system. This was accomplished by analysing the expressio n of a specific marker associated with Langerhans' cells (ATPase) amon g the epidermal portion of cultured sections of mouse skin following t reatment with inhibitors specific for second messenger components and subsequent exposure to UVB. In this study, inhibitors of guanosine tri phosphate (GTP) binding proteins, H-8, pertussis toxin and cholera tox in as well as inhibitors of RNA and protein synthesis were all capable of blocking Langerhans' cell depletion in response to UVB treatment. In contrast, an inhibitor of protein kinase C (H-7) was incapable of s pecifically blocking depletion following treatment with this physical agent. These results suggest that Langerhans' cell depletion mediated by UVB may involve a pertussis and cholera toxin-sensitive G protein a s well as de novo protein synthesis.