Contact sensitivity to Tinuvin P in mice

The contact sensitizing potential of 2-(2'-hydroxy-5'-methylphenyl)benzotriazole (Tinuvin P) was investigated using the murine local lymph node assay (LLNA) and the mouse ear swelling test with some modification in the induction procedure (modified MEST). Topical exposure of the ears to Tinuvin P in acetone:olive oil (AOO) for 3 consecutive days induced no increase in auricular lymph node weight and lymph node cell proliferation. In the LLNA, Tinuvin P was negative, and its sensitizing potential was determined as not strong. In the modified MEST, mice were sensitized with a combination of an intradermal injection of 0.2% Tinuvin P in Freund's complete adjuvant into the shaved abdomen and topical application of 1% Tinuvin P in AOO on both ears for 3 consecutive days. The ear thickness in mice previously treated with Tinuvin P increased significantly on challenge with Tinuvin P. A cross-reaction test between Tinuvin P and various substituted benzotriazole ultraviolet light (UV) absorbers was performed. Challenge with these benzotriazole compounds on the ears of the mice previously sensitized to Tinuvin P showed no increase in ear thickness. These data indicated that Tinuvin P had a contact sensitizing ability, while Tinuvin P-sensitized mice did not cross-react with the other benzotriazole UV absorbers.