Orally induced tolerance to casein in mice on normal mouse chow

Background: Evaluation of immune responses to food proteins in animal models requires that the animals are not already sensitized or orally tolerized against the proteins in question. Since maternal transfer of specific immune responses has been observed, breeding of animals on an antigen-free diet for several generations may be necessary to obtain immunologically naïve animals. Methods: To determine the most appropriate breeding conditions of mice to be used in immunological studies on food proteins, we examined immune responses towards β-lactoglobulin (BLG) in mice bred on a milk-containing diet (F0) and then for three generations (F1–F3) on a commercially available milk-free diet. The specific antibody and cell-proliferative response to BLG was compared in non-immunized and immunized BALB/c mice, and in mice orally tolerized to BLG prior to immunization. Results: The immune response to BLG in the F1 generation deviated from the response observed in the F0 and F2/F3 generations. Importantly, trace amounts of BLG detected in the commercial milk-free diet did not induce oral tolerance. Conclusions: The study showed that breeding mice on an antigen-free diet for at least two generations is required to attain animals appropriate for immunological studies of food proteins. Although the small quantity of BLG in the milk-free diet did not induce detectable oral tolerance in the present study, it is strongly recommended that the potential effect of contaminating dietary antigen is considered in future studies on food proteins.

Section: Discussionsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Effect of Maternal Dietary Cow’s Milk on the Immune Response to β-Lactoglobulin in the Offspring: A Four-Generation Study in Mice

Brix

Christensen

Barkholt

et al. 2005

“…gators that oral tolerance could be induced by protein an tigens in the diet [12,13], Although a systemic humoral re sponse was elicited in the animals fed with the CN diet in our system, this did not exclude the possibility that feeding the CN diet induced oral tolerance. We, therefore, exam ined whether oral tolerance was induced in the CN-fed mice.…”

Section: Induction O F Oral Tolerance By the Cn Dietmentioning

confidence: 97%

Serum Antibody Response Elicited by a Casein Diet is Directed to Only Limited Determinants of αs1-Casein

Kim¹,

Enomoto²,

Hachimura³

et al. 1993

Feeding mice with bovine whole casein as a diet constituent elicited an anti-αs1-casein (αs1-CN) systemic humoral response. The mice fed with the casein (CN) diet responded poorly to subsequent parenteral immunization with the antigen, indicating that oral tolerance was induced in the animals. The serum antibodies elicited by feeding CN were tested for binding to a panel of synthetic peptides and are shown to recognize only a limited number of potential antigenic determinants on αs1-CN. Our results suggest that a similar mechanism may be involved in the onset of milk allergy.

“…Several of the common food allergens, especially those originating from milk and soy, are, however, often present in considerable amounts as standard ingredients in most commercial foods for experimental animals. By use of the classical method of detecting oral tolerance, involving parenteral injection of antigen with adjuvants such as Freund’s or alum, oral tolerance to antigens present in the feed can easily be observed in the animals given the antigen-containing food as a suppressed systemic immune response compared to animals fed an antigen-free diet [11; ]unpubl. data].…”

Section: Introductionmentioning

confidence: 99%

Low-Dose Oral Tolerance due to Antigen in the Diet Suppresses Differentially the Cholera Toxin-Adjuvantized IgE, IgA and IgG Response

Christensen

Kjær

Frøkiær

2003

Background: Cholera toxin (CT) is used as a mucosal adjuvant amongst other applications for studying food allergy because oral administration of antigen with CT induces an antigen-specific type 2 response, including IgE and IgA production. Priorly established oral tolerance due to antigen in the diet may radically impact on the CT-adjuvantized immune response. The present study served to evaluate the effect of priorly established low-dose oral tolerance on the CT-adjuvantized immune response towards a food antigen. Methods: Mice fed a diet containing microgram levels of the soy protein Kunitz soy-trypsin inhibitor (KSTI) (F0 mice) and mice fed a soy-free diet (F2 mice) were orally immunized with KSTI and CT. KSTI-specific serum IgG1, IgG2a, IgA and IgE and fecal IgA were monitored. KSTI-stimulated cell proliferation and interleukin (IL)-6 production were determined. Results: The anti-KSTI IgE and IgA responses in the F0 mice were substantially suppressed, while the IgG1 and IgG2a responses were not suppressed after five oral immunizations. The response suppression tended to decline with increasing numbers of immunizations suggesting that the suppression could be overcome by multiple immunizations. However, cell proliferation and IL-6 production were clearly suppressed even after five immunizations. Conclusions: Priorly established low-dose oral tolerance considerably suppressed the CT-adjuvantized KSTI-specific IgE, IgA and cellular immune response but only weakly and transiently the IgG response. The results revealed that low-dose oral tolerance includes the mucosal IgA response and that CT, albeit mediating an antigen-specific response, does not fully abrogate priorly established oral tolerance.