Acquired oral immune tolerance was overridden by exposure of food antigen via skin to use murine food allergy models

Oral tolerance (OT) was immune regulatory system for foods. Food allergy (FA) patients are induced allergy by inhibition of acquiring OT or overriding OT. Recently, it has been hypothesized that immune tolerance is induced for foods taken orally and that allergy is caused by exposure via skin. In this study, we tried to override OT through exposure of food antigen to skin. We established three murine FA models to analyze the relationship between OT and percutaneous sensitization. IP model: Mice were injected ovalbumin (OVA) intraperitoneally (IP) followed by induction of food allergy. EC model: Mice were pasted a filter paper containing OVA on shaved back skin for epicutaneous sensitization (EC). ID model: Mice were injected OVA intradermally (ID) for sensitization via skin. OT was induced by oral OVA treatment before the sensitization in each model. FA was estimated by drop of body temperature, diarrhea, and OVA-specific IgE level in plasma. In all FA models, we confirmed FA symptoms involving elevation of OVA-specific IgE. OT induction inhibited the increasing in IgE level and suppressed FA in IP model. In EC model with OT induction, we detected increasing in IgE level. In ID model with OT induction, we confirmed FA symptoms and increasing in IgE level. The data indicated that exposure of OVA via skin could override OT.