We trapped a rat (Rattus norvegicus) infected with Capillaria hepatica. At necropsy, grossly yellowish-white nodules (2-3 mm in diameter) were noted to be scattered on the liver's surface. Microscopically, granulomatous and fibrotic nodules that contained the eggs and/or adult worms of Capillaria hepatica were detected in the liver. Septal fibrosis was diffusely formed throughout the liver. There were a number of ED1-positive macrophages located in the sinusoids of the pseudolobules. On the double staining, myofibroblasts and mast cells were generally observed within the fibrous septa with the mast cells in close proximity to the myofibroblasts. We suggest that the interactions between macrophages, myofibroblasts and mast cells play a role in the septal fibrosis observed in rats infected by Capillaria hepatica.
Animals ; *Capillaria ; Enoplida Infections/immunology/parasitology/*veterinary ; Fibroblasts/immunology ; Liver/parasitology/pathology ; Macrophages/immunology ; Mast Cells/immunology ; Rats ; Rodent Diseases/*immunology/*parasitology/pathology

Although some reports have been published on the protective effect of antibodies to Toxoplasma gondii surface membrane proteins, few address the inhibitory activity of antibodies to dense granular proteins (GRA proteins). Therefore, we performed a series of experiments to evaluate the inhibitory effects of monoclonal antibodies (mAbs) to GRA proteins (GRA2, 28 kDa; GRA6, 32 kDa) and surface membrane protein (SAG1, 30 kDa) on the invasion of T. gondii tachyzoites. Passive immunization of mice with one of three mAbs following challenge with a lethal dose of tachyzoites significantly increased survival compared with results for mice treated with control ascites. The survival times of mice challenged with tachyzoites pretreated with anti-GRA6 or anti-SAG1 mAb were significantly increased. Mice that received tachyzoites pretreated with both mAb and complement had longer survival times than those that received tachyzoites pretreated with mAb alone. Invasion of tachyzoites into fibroblasts and macrophages was significantly inhibited in the anti-GRA2, anti-GRA6 or anti-SAG1 mAb pretreated group. Pretreatment with mAb and complement inhibited invasion of tachyzoites in both fibroblasts and macrophages. These results suggest that specific antibodies to dense-granule molecules may be useful for controlling infection with T. gondii.
Animals ; Antibodies, Monoclonal/*pharmacology/therapeutic use ; *Antigens, Protozoan ; Female ; Fibroblasts/parasitology ; Host-Parasite Relations ; Immunization, Passive ; Macrophages/parasitology ; Mice ; Mice, Inbred BALB C ; Protozoan Proteins/*immunology ; Support, Non-U.S. Gov't ; Toxoplasma/*pathogenicity ; Toxoplasmosis/parasitology/*therapy