Abstract: Objective  To investigate the serum levels of IFN-γ and IL-4, and the dynamic changes of IFN-γ-specific and IL-4-specific lymphocytes in mice with Schistosoma japonicum infection after treatment by praziquantel.　　Methods  Ninety BALB/c mice were randomly divided into three groups（n=30） named as infection group, treatment group and control group. The mice in treatment group and infection group were infected with （25±2） S. japonicum cercariae through the abdominal skin. At 6 weeks post-infection, the mice in treatment group were administered orally with praziquantel［300 mg/（kg·d）］ for 3 d. At 4, 6, 8 and 12 weeks post-treatment, the mice were weighed, and serum samples were collected. Serum levels of IFN-γ and IL-4 were measured by ELISA. At the same time, the spleens were aseptically removed to prepare cell suspension, and the counts of IFN-γ and IL-4 specific lymphocytes were examined by ELISPOT after stimulation of Schistosoma japonicum soluble egg antigen（SEA）.  Results  From 4 to 12 weeks after praziquantel treatment, the body weight of mice in treatment group were significantly heavier than that of infection group （P<0.05）, but no significant difference was found between treatment group and control group（P<0.05）. At 4 weeks post-treatment, there was no significant difference in serum levels of IFN-γ and IL-4 between treatment group and infection group（P＞0.05）. At 6, 8, and 12 weeks after treatment, the serum levels of IFN-γ（0.038±0.013, 0.028±0.001, and 0.027±0.007） and IL-4（0.051±0.020, 0.045±0.019, and 0.043±0.016） in treatment group were significantly lower than that of infection group（IFN-γ: 0.057±0.004, 0.060±0.023, and 0.052±0.017; IL-4: 0.150±0.014, 0.148±0.014, and 0.123±0.017）（P＜0.05）. Serum IFN-γ and IL-4 levels in treatment group and infection group were significantly higher than that of control group（P＜0.05）. ELISPOT results showed that at 4, 6 weeks post-treatment, there was no significant difference in the number of IFN-γ-specific lymphocytes between treatment group and infection group（P＞0.05）. While at 8 and 12 weeks after treatment, the IFN-γ-specific lymphocytes in treatment group （39.9±22.8 and 38.5±6.2） were significantly less than that of infection group （141.9±39.3 and 106.8±28.6）（P＜0.05）. At 4-week post-treatment, the IL-4-specific lymphocytes in treatment group were much more than that of infection group（175.6±62.3）（P＜0.05）, and then began to decline. At 8 and 12 weeks after treatment, the IL-4-specific lymphocytes （111.3±14.3 and 113.0±44.2） in treatment group were sig-nificantly less than that of infection group（220.3±107.1 and 208.1±17.2）（P＜0.05）. The IFN-γ-specific and IL-4-specific lymphocytes in treatment group and infection group were significantly more than that of control group（P＜0.05）.  Conclusion  After praziquantel treatment, the serum levels of IFN-γ and IL-4 in mice with S. japonicum infection decrease, and the number of IFN-γ and IL-4 specific lymphocytes reduces.

Key words: Schistosoma japonicum；Praziquantel；IFN-&gamma, ；IL-4；ELISPOT