Distribution of mast cells in relation to Schistosoma japonicum induced lesions in pigs.

The pathogenesis of schistosomiasis japonica has been extensively studied, however only little attention has been paid to the presence and localization of mast cells in relation to Schistosoma japonicum induced lesions. The aim of the present pilot study was to assess the parasitological and pathological responses in S. japonicum infected pigs with emphasis on the description of the distribution of mast cells in relation to lesions in the liver and cecum. Six pigs were exposed to 2,000 cercariae and examined 9 weeks post-infection. Three unexposed pigs of the same age served as helminth free controls. All infected pigs developed granulomatous hepatitis and typhlitis. In the liver, the degree of mast cell infiltration was higher in the infected pigs compared to the unexposed control group. This distinction could not be shown in the cecum. In both the liver and cecum, a mild to moderate number of mast cells were present within the granulomas. A significant relation was found between infection with S. japonicum and the mast cell infiltration in the liver. Due to their possible association with hepatic fibrosis, it seems as if they have some function in the fibrogenic process and thereby play a dual role in the pathogenesis of S. japonicum. In conclusion, the results show that mast cells are recruited to egg induced lesions in both the liver and the cecum.

Phenotypical characterization of intestinal Schistosoma japonicum granulomas in pigs.

The pig has been proposed as a model for human schistosomiasis japonica and the use of this animal model is increasing. The inflammatory response to schistosome infection in the liver and intestine of the pig shows morphological differences, and only the hepatic granulomas have been phenotypically characterized. The aim of the present study was to phenotypically characterize the cellular inflammatory response in the cecum by immunohistochemistry with particular reference to perioval granulomatous reactions in Schistosoma japonicum infected pigs. Six pigs were exposed to 2000 cercariae and examined 9 weeks post-infection. Three uninfected pigs of the same age served as controls. Exposed pigs developed patent infections with the total number of worms between 6 and 110. Cecal granulomas were dominated by CD3 positive T-lymphocytes and IgG positive plasma cells. Despite the difference in the inflammatory response between the liver and the cecum, the results from this study indicate that the phenotypic cellular composition of cecal granulomas appears similar to what has previously been described in the liver.