Role of Maternal Dietary Peanut Exposure in Development of Food Allergy and Oral Tolerance

Background: The impact of maternal ingestion of peanut during pregnancy and lactation on an offspring's risk for peanut allergy is under debate. Objective: To investigate the influence of maternal dietary peanut exposure and breast milk on an offspring's allergy risk. Methods: Preconceptionally peanut-exposed C3H/HeJ females were either fed or not fed peanut during pregnancy and lactation. The offsprings' responses to peanut sensitization or oral tolerance induction by feeding antigen prior to immunization were assessed. We also assessed the impact of immune murine milk on tolerance induction pre- or post-weaning. For antigen uptake studies, mice were gavaged with fluorescent peanut in the presence or absence of immune murine milk; Peyer's patches were harvested for immunostaining. Results: Preconceptional peanut exposure resulted in the production of varying levels of maternal antibodies in serum (and breast milk), which were transferred to the offspring. Despite this, maternal peanut exposure either preconceptionally or during pregnancy and lactation, when compared to no maternal exposure, had no impact on peanut allergy. When offspring were fed peanut directly, dose-dependent tolerance induction, unaltered by maternal feeding of peanut, was seen. Although peanut uptake into the gut-associated lymphoid tissues was enhanced by immune milk as compared to naïve milk, tolerance induction was not affected by the co-administration of immune milk either pre- or post-weaning. Conclusion: Maternal peanut exposure during pregnancy and lactation has no impact on the development of peanut allergy in the offspring. Tolerance to peanut can be induced early, even preweaning, by giving moderate amounts of peanut directly to the infant, and this is neither enhanced nor impaired by concurrent exposure to immune milk.