Topically applied N-acetylcysteine as a protector against UVB-induced systemic immunosuppression.

The potential protective efficacy of N-acetylcysteine against systemic immunosuppression in mice, as a result of UVB exposure, was investigated. The contact hypersensitivity response to trinitrochlorobenzene applied at a distant, non-irradiated site, was used to assess the systemic immunosuppression. Topical application of N-acetylcysteine (0.4-3.2 mumol cm-2), 30 min prior to irradiation (15 kJ m-2), markedly inhibited the UVB-induced immunosuppression. Because N-acetylcysteine does not absorb UVA or UVB radiation, the mechanism of protection must be different from that of sunscreens. The results of this study may have important practical implications in protecting human beings against the deleterious effects of UVB radiation.