Abstract: Objective   To study the difference among immune responses of three kinds of experimental animals with different susceptibility to the infection of Schistosoma japonicum，and preliminarily explore the mechanism of the immune response in permissive and nonpermissive hosts.  Methods   Twelve animals of each kind of rodents，C57BL/6 mice，Sprague Dawley （SD） rats and Microtus fortis，were randomly divided into the infected group and uninfected group each with 6 animals. In infected groups of C57BL/6 mice，SD rats, and M. fortis，each animal was infected with 20，200 and 1 000 cercarie of S. japonicum，respectively. 42 d later，all rodents were sacrificed. Adult worms in portal vein and granulomas in liver were observed and the sera were collected. The levels of cytokines IL-10 and IFN-γ as well as serum IgG，IgG2a, and IgG1 were detected by ELISA .  Results   At the 42th day post infection，worms in portal vein and liver granulomas were observed in C57BL/6 mice and SD rats, but not in M. fortis. The level of IL-10 in the sera of SD rats ［（2.21±0.12） pg/ml］ was significantly higher than that in the sera of M. fortis ［（1.64±0.39） pg/ml］ and C57BL/6 mice［（0.10±0.04） pg/ml］ （P < 0.01）. IL-10 in the sera of M. fortis was also significantly higher than that in the sera of C57BL/6 mice （P<0.01）. IFN-γ in the sera of SD rats ［（0.21±0.11） pg/ml］ was significantly higher than that in the sera of M. fortis ［（0.11±0.03） pg/ml］ and C57BL/6 mice ［（0.09±0.02） pg/ml］ （P<0.05）, but no difference between M. fortis and C57BL/6 mice （P>0.05）. The levels of IgG （1.53±0.31）， IgG1 （1.48±0.44） and IgG2a （0.41±0.11） in SD rats were significantly higher than that in the sera of M. fortis （0.48±0.14， 0.15±0.03 and 0.12±0.06l） （P<0.01）. The levels of IgG （1.21±0.16）， IgG1 （0.88±0.31） in C57BL/6 mice were significantly higher than that in the sera of M. fortis （P<0.01）. IgG1 antibody is the predominant subclass in the three kinds of rodents. The levels of IL-10, IFN-γ and antibody subclass IgG, IgG1, IgG2a in all noninfected rodents were not detected.  Conclusion  IL-10 in nonpermissive hosts，which is an essential agent in the regulation of Th2 immune response，is higher than that in permissive host. It may play an important role in the resistance to schistosome in the nonpermissive hosts.

Key words:  , Schistosoma japonicum；Permissive host；Non-permissive host；Immune；T helper cell 2