Oral mucosa effectively protects against peanut allergy in mice

Background Oral consumption of peanut products early in life reduces the incidence of peanut allergy in children. However, little is known about whether exposure via the oral mucosa alone is sufficient, or if the gastrointestinal tract must be engaged to protect against peanut allergy. Objective We used a mouse model and examined the effects of peanut allergen administration only to the oral cavity on allergy development induced by environmental exposure. Methods Naïve BALB/c mice were administered peanut flour (PNF) sublingually, followed by epicutaneous exposure to PNF to mimic a human condition. The sublingual volume was adjusted to engage only the oral cavity and prevent it from reaching the esophagus or gastrointestinal tract. The efficacy was evaluated by examining the anaphylactic response, antibody titers, and T follicular helper (Tfh) cells. Results The mice exposed epicutaneously to PNF developed peanut allergy as demonstrated by increased plasma levels of peanut-specific IgE and the manifestation of acute systemic anaphylaxis upon intraperitoneal challenge with peanut extract. The development of peanut allergy was suppressed when mice had been given PNF sublingually before epicutaneous exposure. There were fewer Tfh cells in the skin-draining lymph nodes of mice that received sublingual PNF compared with PBS. Suppression of IgE production was observed with sublingual PNF at one-tenth of the intragastric PNF dose. Discussion Administration of peanut allergens only to the oral cavity effectively prevents the development of peanut allergy. The capacity of the oral mucosa to promote immunologic tolerance needs to be evaluated further to prevent food allergy.