Analysis of egg granuloma formation in Schistosoma japonicum-infected mice treated with antibodies to interleukin-5 and gamma interferon.

Schistosoma japonicum-infected mice were treated with antibodies to interleukin-5 (IL-5) or gamma interferon (IFN-gamma) from week 3 or 4 to week 10 of infection. Neither antibody affected egg production by the parasite, and neither had a consistent effect on the secretion of IFN-gamma or IL-5 cell-related cytokines by spleen cells from infected mice. Mice treated with antibody to murine IL-5 had only rare eosinophils in hepatic circumoval granulomas. Granulomas around single eggs were reduced in volume by a third, but hepatic fibrosis was unaffected. Treatment with antibody to murine IFN-gamma also reduced the size of granulomas and also did not affect hepatic fibrosis, which was measured as hydroxyproline. Our results, taken together with the studies of others, indicate that a complex interaction of cytokines affects granuloma size and that the size and fibrosis of granulomas are to some extent regulated independently.