The effects of T-cell deficiency on host survival and granuloma formation in the liver of mice infected with Schistosoma japonicum

Objective To observe host survival time and egg granuloma formation in the liver of T-cell deprived mice infected with Schistosoma japonicum. Methods Twenty T-cell deprived mice (nu/nu) and 20 BALB/c mice were used. Mice in both groups were infected with 25±1 S. japonicum cercariae and their survival time after the challenge was recorded. Seven mice in each group were randomly selected and sacrificed on day 42 after the challenge to count the eggs in the liver and to histologically examine single egg granulomas in the liver and determine their size. Results The survival time of all 20 nude mice after infection was no more than 46 days. The number of eggs per pair of worms in the liver of nude mice was significantly lower (4 759.5±2 161.3) than that in BALB/c mice(7 323.4±2254.6)(P0.05). Egg granulomas in the livers of nude mice were ill-defined. Single egg granulomas in the liver of nude mice were significantly smaller(138.4±31.9) μm than those in BALB/c mice (316.4±68.2) μm (P0.01). A significant and selective decrease in the number of eosinophils within the granulomas was noted in nude mice in comparison to BALB/c mice. In addition,hepatocyte necrosis in the vicinity of eggs was obvious in nude mice. Conclusion T cells play an important role in egg granuloma formation and prolong the survival of mice infected with S. japonicum.