PROTECTION AGAINST ULTRAVIOLET-B RADIATION-INDUCED LOCAL AND SYSTEMICSUPPRESSION OF CONTACT HYPERSENSITIVITY AND EDEMA RESPONSES IN C3H HEN MICE BY GREEN TEA POLYPHENOLS/

Exposure of skin to UV radiation can cause diverse biological effects, including induction of inflammation, alteration in cutaneous immune c ells and impairment of contact hypersensitivity (CHS) responses. Our l aboratory has demonstrated that oral feeding as well as topical applic ation of a poly phenolic fraction isolated from green tea (GTP) afford s protection against the carcinogenic effects of UVB (280-320 nm) radi ation. In this study, we investigated whether GTP could protect agains t UVB-induced immunosuppression and cutaneous inflammatory responses i n C3H mice. Immunosuppression was assessed by contact sensitization wi th 2,4-dinitrofluorobenzene applied to UVB-irradiated skin (local supp ression) or to a distant site (systemic suppression), while double ski n-fold swelling was used as the measure of UVB-induced inflammation. T opical application of GTP (1-6 mg/animal), 30 min prior to or 30 min a fter exposure to a single dose of UVB (2 kJ/m(2)) resulted in signific ant protection against local (25-90%) and systemic suppression (23-95% ) of CHS and inflammation in mouse dorsal skin (70-80%). These protect ive effects were dependent on the dose of GTP employed; increasing the dose (1-6 mg/animal) resulted in an increased protective effect (25-9 3%). The protective effects were also dependent on the dose of UVB (2- 32 kJ/m(2)). Among the four major epicatechin derivatives present in G TP, (-)-epigallocatechin-3-gallate, the major constituent in GTP, was found to be the most effective in affording protection against UVB-cau sed CHS and inflammatory responses. Our study suggests that green tea, specifically polyphenols present therein, may be useful against infla mmatory dermatoses and immunosuppression caused by solar radiation.