title: Oral administration of IL-12 abrogates the induction but not the maintenance of oral tolerance.
abstract: BACKGROUND
  IL-12 is a Th1-inducing cytokine and known to be induced by some food factors. This function of such foods is expected to be applied for antiallergic materials. However, the influence of IL-12 on the immune responses has not been fully investigated. Oral tolerance is an immunologically unresponsive state induced by orally administered food antigens. Although a failure in the induction of oral tolerance would result in food allergy, the mechanisms for the induction and abrogation of oral tolerance have not been clarified. IL-12 induced by food factors may also affect the induction of oral tolerance. In this study we examined the effect of the oral administration of IL-12 on the induction and maintenance of oral tolerance.
  
  
  METHODS
  BALB/c mice were fed beta-lactoglobulin with or without IL-12. After immunizing them with the antigen, the serum antibody titer of these mice was measured to evaluate the induction of oral tolerance.
  
  
  RESULTS
  The induction of oral tolerance was prevented in the mice that had been simultaneously fed the antigen and IL-12. On the other hand IL-12 did not abrogate the already established oral tolerance when it was administered after feeding the antigen. We also found that oral tolerance could be induced normally in mice that had failed to induce such tolerance by simultaneous feeding of IL-12 and the antigen.
  
  
  CONCLUSIONS
  The results indicate that IL-12 induced in the intestine by some food factors is involved in the regulation of oral tolerance.
authors.affiliation: Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Tokyo, Japan. tyoshi@cc.tuat.ac.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshida
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Uno
authors.forename: Aki
authors.initials: A
authors.lastname: Hirano
authors.forename: Hanae
authors.initials: H
authors.lastname: Wada
authors.forename: Koji
authors.initials: K
authors.lastname: Takahashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Hattori
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000917:Antibody Formation / Q000187:drug effects; D017635:Clonal Anergy / Q000187:drug effects / Q000276:immunology; D018920:Coculture Techniques; D004044:Dietary Proteins / Q000008:administration & dosage / Q000276:immunology; D018985:Epitopes, B-Lymphocyte / Q000276:immunology; D005260:Female; D007108:Immune Tolerance / Q000187:drug effects*; D007074:Immunoglobulin G / Q000097:blood; D018664:Interleukin-12 / Q000008:administration & dosage / Q000494:pharmacology*; D007782:Lactoglobulins / Q000008:administration & dosage / Q000276:immunology; D008198:Lymph Nodes / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D013154:Spleen / Q000166:cytology / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D014611:Vaccination
chemical_list: D004044:Dietary Proteins; D018985:Epitopes, B-Lymphocyte; D007074:Immunoglobulin G; D007782:Lactoglobulins; D018664:Interleukin-12