Long-term antibiotic treatment attenuates the development of food allergy in a murine model.

While short-term antibiotic exposure has been reported to exacerbate the development of allergies, the effects of long-term administration remain less understood. This study addressed the influences of prolonged antibiotic administration in a murine model of food allergy. Mice received a broad-spectrum antibiotic cocktail (ABX) for six weeks from presensitization through allergen challenge. ABX reduced allergic reactions, serum IgE levels, and intestinal mast cell counts. Production of Th2 cytokine, but not of Th1 and Th17 cytokines, was lowered in allergen-stimulated splenocytes of ABX-treated allergic mice, whereas the levels of these cytokines in their intestines decreased. ABX did not significantly alter the levels of regulatory cytokine IL-10 in intestines and regulatory T cells in spleens. ABX reduced gut bacterial amount, though Lactobacillus, Lactococcus, and Streptococcus remained detectable. Collectively, long-term ABX suppresses allergic reaction by modulating Th2-mediated events dominantly, providing insights into the complex role of antibiotics in allergy models.