Oral administration of IL-12 abrogates the induction but not the maintenance of oral tolerance.
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.
Yoshida
Tadashi
T
Department of Applied Biological Science, Tokyo University of Agriculture and Technology, Tokyo, Japan. tyoshi@cc.tuat.ac.jp
Uno
Tsukasa
T
Hirano
Aki
A
Wada
Hanae
H
Takahashi
Koji
K
Hattori
Makoto
M
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
D004044:Dietary Proteins; D018985:Epitopes, B-Lymphocyte; D007074:Immunoglobulin G; D007782:Lactoglobulins; D018664:Interleukin-12