title: Oral tolerance in humans. T cell but not B cell tolerance after antigen feeding.
abstract: The purpose of this study was to investigate whether oral tolerance, defined as Ag-specific immunologic unresponsiveness after Ag feeding, could be induced in humans after prolonged Ag ingestion. Eight adult volunteers ingested a total dose of 0.5 g of keyhole limpet hemocyanin (KLH) followed by subcutaneous immunization with KLH. Eight controls received only the subcutaneous immunization. In the group fed KLH, there was a significant reduction in KLH-specific T cell proliferation (p = 0.04) and delayed skin test responses (p = 0.07) to KLH. KLH ingestion alone did not induce significant levels of Abs in either serum or secretions. However, after the subsequent subcutaneous immunization, the number of circulating IgG and IgM anti-KLH-producing cells, the titers of serum IgG, IgA, and IgM anti-KLH Abs, and the titers of IgA anti-KLH Abs in saliva and intestinal secretions were significantly greater in the KLH-fed group than in the nonfed group. We conclude that KLH feeding induced systemic T cell tolerance, but B cell priming, at both systemic and mucosal sites. These studies support the concept of using Ag feeding as a treatment for certain immune-mediated diseases.
authors.affiliation: Department of Medicine, University of Alabama at Birmingham 35294.
authors.forename: S
authors.initials: S
authors.lastname: Husby
authors.forename: J
authors.initials: J
authors.lastname: Mestecky
authors.forename: Z
authors.initials: Z
authors.lastname: Moldoveanu
authors.forename: S
authors.initials: S
authors.lastname: Holland
authors.forename: C O
authors.initials: CO
authors.lastname: Elson
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000917:Antibody Formation; D000941:Antigens / Q000008:administration & dosage*; D001402:B-Lymphocytes / Q000276:immunology*; D005260:Female; D006433:Hemocyanins / Q000008:administration & dosage / Q000276:immunology; D006801:Humans; D006968:Hypersensitivity, Delayed; D007108:Immune Tolerance; D007114:Immunization; D066298:In Vitro Techniques; D007279:Injections, Subcutaneous; D007413:Intestinal Mucosa / Q000276:immunology; D008213:Lymphocyte Activation; D008297:Male; D012463:Saliva / Q000276:immunology; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D000941:Antigens; D006433:Hemocyanins; C032808:keyhole-limpet hemocyanin