title: Studies of tolerance in schistosomiasis.
abstract: We have studied the induction of immune tolerance by exogenous exposure to schistosomal egg antigen (SEA). We compared routes of administration, exposure to different forms of SEA (eggs, normal SEA, reultracentrifuged SEA), and treatment schedules. Tolerance was evaluated in comparison to SEA sensitization, after challenge with SEA or eggs. Anti-SEA responses were measured by ELISA assays, and cell-mediated responsiveness by 24-hr skin tests and pulmonary granuloma formation 8 and 16 days after intravenous egg injection. Oral administration of either SEA in PBS or NaHCO3, or eggs in PBS did not induce tolerance or sensitization. Reultracentrifuged SEA was similar to SEA in inducing cell-mediated immune response. Intrathymic exposure to SEA either had no effect or sensitized the animal for subsequent exposure to SEA. Two intraperitoneal injections of 0.5 to 1.0 mg of SEA lead to reduced cell-mediated responses, but resulted in high levels of anti-SEA antibody, suggesting a state of split tolerance or immune deviation. Our studies suggest that with complex, poorly defined antigens such as SEA, many of the classic methods of eliciting tolerance fail. The biologic significance of the form of tolerance inducible by high doses of SEA remains to be defined.
mesh_terms: D000818:Animals; D000906:Antibodies / Q000032:analysis; D000947:Antigens, Helminth / Q000276:immunology; D007108:Immune Tolerance; D007111:Immunity, Cellular; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D010063:Ovum / Q000276:immunology; D012552:Schistosomiasis / Q000276:immunology*
chemical_list: D000906:Antibodies; D000947:Antigens, Helminth