Allergen mimotopes in food enhance type I allergic reactions in mice

BIP1 is a murine IgG antibody capable of enhancing the IgE binding to Bet v 1, the major birch pollen allergen, We have previously generated a mimotop e of BIP1, designated Bet mim 1, from a constrained phage display peptide l ibrary. We dem onstrated that oral immunization of BALB/c mice with the Bet mim 1 mimotope resulted in the induction of Bet v I-specific IgG, The aim of this study was to test the influence of such an oral immunization with B et mim 1 on a subsequent type I allergic response to Bet v 1, Phages displa ying Bet mim 1 or control mimotopes, or PBS alone, were delivered to BALB/c mice by intragastric gavages prior to systemic sensitization with recombin ant Bet v I and AI(OH),, an adjuvant inducing preferentially IgE antibody r esponses. Only mice fed with Bet mim 1-phages displayed substantially enhan ced type I allergic skin reactivity to Bet v 1, as compared to mice pretrea ted with control mimotopes or PBS, A gastric digestion assay indicated that Bet v I and its homologue from apple, Mal d 1, were degraded within second s under physiological conditions. In contrast, phage-displayed mimotopes we re resistant to digestion. Our data indicate that allergen mimics in the di et that resist digestion, can induce allergen specific IgG able to enhance an allergic response. We therefore conclude that sensitization via the oral route may represent a mechanism for aggravating type I allergic reactions, probably leading to an earlier onset of symptoms even at lower allergen do sage.