Abstract: Objective To observe the changes of peripheral blood T lymphocytes， IFN-γ, TNF-α and IL-4 in rats infected by T. gondii. Methods 48 Sprague-Dawley（SD） rats were intra-abdominally injected with 2×10⁵/L of cellulose purified living tachyzoites in 2 ml and randomly divided into 8 groups. Six rat was intra-abdominally injected 2 ml of saline as control and 4 rats were remained as normal control. Peripheral blood was collected and the level of IFN-γ, TNF?-α, IL-4 was analyzed by ELISA on day 1, 3, 7, 14, 28, 35, 42, 60. Results Level of IFN-γ （6.73 pg/ml） and IL-4 （6.91 pg/ml） increased in experimental rats on day 7 （P<0.05） and maintained. Level of TNF-α （14.37 pg/ml） increased in experimental rats on day 28 （P<0.05）， and that of CD8+ T lymphocytes （14.22%） was significantly lower than that in control （23.08%） （P<0.05） and recovered on day 28. No considerable change was observed on the level of CD4+ T lymphocytes. Conclusion The level of CD8+ T lymphocytes, IFN-γ, TNF-α and IL-4 in the rat can be affected by the infection of T. gondii and the level of CD4+ T lymphocytes shows no change.

Key words: Toxoplasma gondii, ELISA, Flow cytometry, CD4+, CD8+ T lymphocyte, IFN-γ, TNF-α, IL-4