UV Treatment of Skin: Effect on Langerhans Cells and HSV-1 Infection

The effects of ultraviolet (UV) irradiation of the skin on herpes simplex virus (HSV) infection were investigated. Exposure of the skin to UV-B resulted in a transient dose-dependent reduction of the number of la-positive epidermal cells (EC). This decrease of Ia antigen expression of EC was accompanied by a parallel loss of antigen-presenting capacity of EC, which was represented by HSV-induced T-cell proliferative response stimulated by EC. Immune T cells antigen-stimulated in the presence of normal EC effectively cleared HSV from intradermally infected nude mice, while those antigen-stimulated in the presence of UV-irradiated EC did not. In addition UV irradiation of mice at the inoculation site of HSV increased the severity of acute infection and the incidence of latency. These findings indicate that in vivo UV irradiation of the skin abrogates the immune function of EC both in vitro and in vivo, and affects HSV pathogenesis.