The effects of high-dose UV exposure on murine Langerhans cell function at exposed and unexposed sites as assessed using in vivo and in vitro assays

Abstract

Exposure of mice to a single large dose of UV radiation leads to a systemic inability of these mice to develop effective contact hypersensitivity (CS) responses to epicutaneously applied dinitrofluorobenzene (DNFB). Although this effect requires time to develop when unirradiated skin sites are used for CS sensitization, it is observed immediately at the site of UV exposure. Unirradiated skin sites on mice exposed to a single large dose of UV radiation 3 days previously were found to contain histochemically detectable ATPase+ cells with normal morphology and in normal densities, and yet CS responses were not induced to DNFB applied to these sites. Epidermal cells (EC) obtained from these skin sites were found to be capable of providing accessory cell (AC) function in in vitro T-cell proliferation assays that was qualitatively similar to EC obtained from unirradiated mice, thus indicating that exposure of mice to a single large dose of UV radiation does not induce a systemic AC dysfunction. Indeed, increased levels of AC activity were obtained in EC prepared from the UV-irradiated skin sites on the third day following UV exposure. This latter effect may be due to an influx of inflammatory cells into the irradiated site in response to the tissue damage caused by the UV radiation. We hypothesize that the inflammatory response induced by the cytodestructive effects of the UV treatment may play a central role in the generation of the systemic suppression of induction of CS responses, perhaps through the induction of acute-phase proteins.