SOUTHEAST ASIAN J TROP MED PUBLIC HEALTH 630 Vol 37 No. 4 July 2006 Correspondence: Tine Iburg, Laboratory of Pathol- ogy, Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, Ridebanevej 3, DK-1870 Frederiksberg C, Denmark. Tel: +45 35283129; Fax: +45 35353514 E-mail: tib@kvl.dk INTRODUCTION Schistosoma japonicum is the agent of an important zoonotic infection affecting both people and domestic as well as wild animals in endemic areas in Southeast Asia, mainly China and the Philippines (Fernandez et al, 1982; Ross et al, 1997; Jiang et al, 2002). In- fection of a host results in granulomatous in- flammation in the liver and intestine, and sub- sequent hepatic fibrosis following deposition of eggs in the mesenteric and portal veins (King, 2001). Since the pig is a natural host of S. japonicum and because of its anatomical, DISTRIBUTION OF MAST CELLS IN RELATION TO SCHISTOSOMA JAPONICUM INDUCED LESIONS IN PIGS Malene M Birck, Susanne Pors 1 , Maria V Johansen 2 and Tine Iburg 1 1 Laboratory of Pathology, Department of Veterinary Pathobiology, The Royal Veterinary and Agricultural University, Frederiksberg, Denmark; 2 DBL-Institute for Health Research and Development, Charlottenlund, Denmark Abstract. The pathogenesis of schistosomiasis japonica has been extensively studied, how- ever 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 unex- posed 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 he- patic 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. physiological and immunological similarities to man, it is considered an appropriate and rel- evant model for S. japonicum research (Willingham and Hurst 1996; Johansen et al, 2000). Recruitment of mast cells is a common feature of helminth infections (Lee et al, 1986). However the role, presence and localization of mast cells in relation to egg-induced lesions caused by S. japonicum have not received much attention in previous studies. Contrary to S. japonicum research, mast cells have re- ceived more attention in experimental studies conducted with S. mansoni (Weinstock and Boros, 1983a; Reis et al, 2001; De Jonge et al, 2002; Metwali et al, 2002). Also in a study of human liver biopsies, mast cells were abun- dant in livers from schistosome infected indi- viduals compared to other granulomatous in- fections (Celasun et al, 1992). The aim of this pilot study was to evaluate the parasitological