title: Immune response versus mucosal tolerance to mucosally administered antigens.
abstract: The enhancement of protective mucosal responses to infectious agents sought by vaccinologists, and the desired suppression of immune responses to autoantigens, allergens and food antigens induced by mucosal exposure to relevant antigens, may seem paradoxical. However, such outcomes are not mutually exclusive because of a hierarchy in the quality of immune responses: mucosal immunity manifested by the appearance of secretory antibodies and systemic tolerance manifested by diminished cell-mediated responses may be induced concomitantly. We have demonstrated that the ingestion, or nasal application, of a neo-antigen-keyhole limpet hemocyanin (KLH)-primes human volunteers for subsequent humoral mucosal and systemic responses induced by systemic immunization but suppresses cell-mediated responses (T cell proliferation and delayed-type hypersensitivity). Furthermore, extended ingestion of selected food antigens diminished, but did not totally suppress, cell-mediated immunity and levels of serum antibodies while salivary antibodies were easily detectable. Most importantly, the humoral and cellular immune responses induced by systemic immunization with KLH could not be suppressed by subsequent extended ingestion of large doses of the same antigen. Thus, ongoing systemic responses are refractory to the induction of mucosal tolerance in humans. This finding is of considerable importance for the development of and sequence of immunization with mucosally administered vaccines.
authors.affiliation: Department of Microbiology--BBRB 757, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294 2170, USA. mestecky@uab.edu
authors.forename: Jiri
authors.initials: J
authors.lastname: Mestecky
authors.forename: Zina
authors.initials: Z
authors.lastname: Moldoveanu
authors.forename: Charles O
authors.initials: CO
authors.lastname: Elson
mesh_terms: D000818:Animals; D000941:Antigens / Q000008:administration & dosage* / Q000276:immunology*; D006801:Humans; D007108:Immune Tolerance / Q000276:immunology*; D018928:Immunity, Mucosal / Q000276:immunology*; D007117:Immunization, Secondary
chemical_list: D000941:Antigens