Abstract: 　Objective To study the effects of the monoclonal anti idiotypic antibody NP30 active immunization on egg granuloma formation and hepatic fibrosis in Schistosoma japonicum infection. Methods ICR mice were actively immunized with NP30 100 μg ×3 ip. every 10 days while the mice in control group were injected with SP2/0 ascites ip. simultaneously. After cercariae challenging,the mice were killed at the 4th, 8th,12th, 16th, 20th and 24th week, respectively.Mouse livers were removed and stained histochemically with VG and subjected to immunohistochemical assay of collagen type Ⅰ,Ⅲ and fibronectin(FN).The volume of egg granulomas and the content of collagen type Ⅰ,Ⅲ and FN were determined quantitatively by NYD 1000 Image Analysis System. Results The volume of egg granulomas in NP30 immunized group was much smaller than that of control group from the 12th week after cercariae challenge. The cellular components of egg granulomas in NP30 immunized group were significantly different from those of the control group,exhibiting two types of atypical egg granulomas were found.VG stain revealed that the average optical density of collagen in hepatic granulomas of experimental group was lower than that of control group.Immunohistochemical assay revealed that the contents of collagen type Ⅰ,Ⅲ and fibronectin in egg granulomas of experimental group were lower than those of control group. Conclusion NP30 vaccination may induce both cellular and humoral protective immunity to modulate egg granulomas and suppress liver fibrosis of schistosomiasis japonica.

Key words: Schistosoma japonicum, anti idiotypic antibody, egg granuloma, hepatic fibrosis, immunohistochemistry, quantitative image analysis