Inhibition of Allergen-Induced Airway Inflammation by Low-Dose Oral Immunotherapy with Transgenic Rice Seeds Independently of Immunoglobulin E Synthesis

Abstract

Background: Oral immunotherapy is potentially useful for the treatment of allergic diseases. We previously demonstrated that allergen-induced airway inflammation and immunoglobulin E (IgE) production in mice were suppressed by oral administration of high-dose transgenic (Tg) rice seeds (approximately 50 g/kg/day) expressing a T cell epitope of Dermatophagoides pteronyssinus group 1 allergen (Der p 1). However, this amount of Tg rice seeds was not realistic in our daily life. In this study, allergen-induced airway inflammation and IgE production following oral immunotherapy with a realistic (lowest) dose of Tg rice seeds were investigated. Methods: Mice orally administered with Tg or non-Tg rice seeds at approximately 5 g/kg/day for 1 week were immunized with recombinant Der p 1, and then challenged with the corresponding allergen. The infiltration of inflammatory cells into the airways and the levels of allergen-specific serum IgE were examined. Results: Low-dose oral administration of Tg rice seeds significantly inhibited the allergen-induced infiltration of eosinophils and lymphocytes into the airways, but allergen-specific IgE synthesis was not changed. Conclusions: Low-dose oral immunotherapy with Tg rice seeds could suppress allergen-induced airway inflammation through mechanisms other than the downregulation of IgE synthesis.