Abstract: AIM: To observe effects of roxithromycin on contact sensitivity induced by picryl chloride (PCl) and on the functions of T cells.METHODS: Contact sensitivity was induced with picryl chloride, two-way mixed lymphacyte reaction and Concanavalin A were used to induce T cell proliferation. The viability and cell pro-liferation were examined by MTT method, mRNA expres-sion was analyzed by RT-PCR and densitometry. RESULTS: Roxithromycin 20 mg°kg^-1 significantly sup-pressed contact sensitivity induced by picryl chloride in mice. In vitro assay, roxithromycin dose-dependently in-hibited splenic T lymphocyte proliferation induced by con-canavalin A, 5 and 25μg°ml^-1 of roxithromycin sup-pressed mRNA expressions of T-bet, IL-2 and IFN-γ.25 μg°ml^-1 of roxithromycin also decreased two-way mixed lymphocyte reaction.CONCLUSION: Roxithromycin suppresses picryl chloride-induced contact sensitivity. The inhibitory effect may be related to the suppression on the viability, activation and proliferation of T lympho-cytes.

Key words: roxithromycin, contact sensitivity, two-way mixed lymphacyte reaction, T lymphocyte prolifera-tion, mRNA expression