[Changes of IFN-gamma, IL-4 and T cells in Schistosoma japonicum-infected mice after praziquantel treatment].

Objective: To investigate the serum levels of IFN-gamma and IL-4, and the dynamic changes of IFN-gamma-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 x 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-gamma 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-gamma 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 posttreatment, there was no significant difference in serum levels of IFN-gamma 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-gamma (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-gamma: 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-gamma 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-gamma-specific lymphocytes between treatment group and infection group (P > 0.05). While at 8 and 12 weeks after treatment, the IFN-gamma-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 significantly less than that of infection group (220.3 +/- 107.1 and 208.1 +/- 17.2) (P < 0.05). The IFN-gamma-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-gamma and IL-4 in mice with S. japonicum infection decrease, and the number of IFN-gamma and IL-4 specific lymphocytes reduces.