Dynamic analysis of T-lymphocyte function in relation to hepatopathologic changes and effect of interleukin-12 treatment in mice infected with Schistosoma japonicum

We analyzed the dynamics of splenic T-lymphocyte function in relation to he patopathologic changes in C3H/He mice, experimentally infected with Schisto soma japonicum. Vigorous granuloma formation was observed at 7 wk postinfec tion. At 10 wk postinfection, granuloma formation entered into the down mod ulation stage, as represented by the diminished granuloma size. The Th2 res ponse was activated when eggs appeared in the liver, whereas Th 1 responses were depressed and the proliferation of T lymphocytes was decreased. The l evel of IgG antibodies to the worm and egg antigens rose continually after infection. interleukin-12 treatment of infected mice inhibited Th2 response s and T-cell proliferation, decreased granuloma formation and fibrosis, but had no effect on the fecundity of the worms. These data suggest that egg d eposition is the major factor driving Th2 responses, depressing Th1 cytokin e expression as well as T-cell proliferation in S. japonicum-infected mice.