Immunomodulatory effects of ultraviolet B irradiation on atopic dermatitis in NC/Nga mice

BACKGROUND: Atopic dermatitis (AD) is a common pruritic inflammatory skin disease, which occurs primarily in childhood. Recently, narrow-band ultraviolet B (UVB) phototherapy has been used to treat AD, but the mechanism involved is unknown. In this study, we investigated whether UVB irradiation influences AD in the NC/Nga mouse. METHODS: The mice were separated into three groups: control, AD-control (immunized with mite antigens), and AD+UVB-irradiated (immunized with mite antigens and UVB irradiation) groups. The mice in the irradiation group were exposed to 1 kJ/m(2)/day twice a week from 6 to 12 weeks of age. Animals in the control and AD-control groups were shaved, but not irradiated. RESULTS: In the AD+UVB-irradiated group, the atopy score, ear thickness, and total immunoglobulin E (IgE) were increased in comparison with the AD-control group. On day 40, the levels of interleukin (IL)-4, IL-5, and IL-10 in the spleen lymphocytes were significantly increased compared with the AD-control group, resulting in a marked decrease of the interferon (IFN)-gamma/IL-4 ratio compared with the AD-control group. In addition, the levels of IL-6, tumor necrosis factor (TNF)-alpha, and NO(x) production by peritoneal macrophages were significantly elevated. CONCLUSION: These results indicate that UVB irradiation promotes the development of AD-like skin lesions in NC/Nga mice.