The Presence of Host Immunoglobulins in Hydatid Cyst Membranes

Abstract

Mouse and sheep IgC immunoglobulins were detected, by the immunoelectrophoresis test, in the membranes of hydatid cysts obtained from these 2 host species. Three months after transplantation of mouse hydatid cysts into guinea pigs both donor and recipient immunoglobulins were detected in the parasite membranes. These observations are discussed in terms of the current hypotheses on parasite survival, penetration of host macromolecules into hydatid cysts, the chemical analysis of cestode protein structure, and hydatid serology. The ability of parasites to survive for extended periods of time within the tissues of immunologically competent animals has become a central issue in immunoparasitology. Several hypotheses have been put forth to account for this phenomenon, based upon either antigenic sharing between host and parasite as a result of natural selection (Sprent, 1962; Dineen, 1963; Damian, 1964), host induction (Capron et al., 1968), phenotypic adaptation (Smithers and Terry, 1969), or to bound host antibody (Varela-Diaz et al., 1972). The present study was designed to determine if host immunoglobulins are detectable in the membranes of cysts of Echinococcus granulosus, and the results are discussed in relation to the above hypotheses, studies on cestode protein structure, and penetration of immunoglobulins into hydatid cysts. MATERIALS AND METHODS Collection of hydatid cyst membranes Fertile hydatid cysts were collected from the livers and lungs of sheep at slaughter. The fibrous external capsules of host origin were dissected apart and the parasite cyst walls removed. Only cyst membranes of healthy appearance were selected and areas adhering to the host capsule were discarded. Parasite membranes were also obtained from sterile peritoneal hydatid cysts in mice with experimental secondary infections of 5 months standing. Five healthy, viable, sterile cysts were also obtained from these mice and each transplanted into the peritoneal cavity of an adult guinea pig. These recipient animals were necropsied 3 months later and the cyst membranes collected. The external capsules of host origin were removed from all cysts and discarded in all cases. Received for publication 13 January 1972. 484 Processing of cyst membranes Membranes from sheep hydatid cysts were cut into 1-cm2 pieces and placed in 500-ml Erlenmeyer flasks. A glass tube connected to a faucet at one end was inserted into the bottom of the flask. After covering the mouth of the flask with gauze, the faucet was opened and the cyst material subjected to a constant flow of water (at a rate of 20 liters per hour). After washing for 48 hr the membranes were ground in a Vortex and the homogenate diluted to contain 1 mg wet weight of membrane per milliliter. The membranes obtained from mouse cysts and from mouse cysts transplanted into guinea pigs were processed in the same manner. A sample of supernatant water was also collected at the end of the washing of each membrane suspension. Production of antisera Emulsions were prepared consisting of each hydatid cyst membrane homogenate in equal volumes of Freund's complete adjuvant. Antisera were prepared by injecting rabbits intramuscularly at weekly intervals for 4 weeks with 2 ml of homogenate. Antisera to the supernatant water from each membrane suspension were prepared in the same