Abstract: 　Objective To detect the expression of IL-2 and TNF-α in the liver at different period postinfection of Schis-tosoma japonicum and their effect on liver fibrosis after supplementary injection of these cytokines. Methods Mice were infected with schistosome cercariae and divided into 3 groups. Two groups were injected (ip) every other day with IL-2 and TNF-α respectively for consecutive 4 wk. The third group and an uninfected group of normal mice were regarded as control. The ABC immunohistochemistry and pathologic image multimedia quantification system were applied to detect activity of IL-2 and TNF-α. Results The level of IL-2 and TNF-α in the liver in infected but untreated group slowly decreased (from 8, 11, 14 to 18 wk). The supplementary injection of the cytokines at 6 wk postinfection in the two groups increased the cytokines significantly, the level of IL-2 or TNF-αwas higher at 1 - 8 wk after the last injection than that of both infected and uninfected control groups (P<0.01). The granulomatous inflammation and fibrosis in the livers of the two groups were slighter than that of the control. Conclusion At the 6th wk postinfection with egg deposition, exogenous supplementation with TNF-αor IL-2 induces enhanced expression of the two kinds of cytokines, corresponding to a diminished degree of the liver granulomatous inflammation and fibrosis.

Key words: Schistosoma japonicum, IL-2, TNF-α, liver fibrosis