Early allergen introduction overrides allergy predisposition in offspring of horses withhypersensitivity.

Abstract

INTRODUCTION: The origins of allergy are both genetic and environmental. We performed a full-sibling study to determine the role of early-in-life or delayed allergen introduction onhypersensitivity development in a cohort with history of an allergic phenotype and Culicoides hypersensitivity. IgE-mediated allergies naturally develop in many mammalian species, and we used a horse model of allergy calledhypersensitivity.hypersensitivity is a seasonal, recurrent, IgE-mediated allergy caused by the salivary proteins of bitingmidges. METHODS: The study included four cohorts that lived together in the same environment, only differing in the timing of allergen exposure and the transfer of allergen-specific maternal antibodies. The parent cohort was first exposed to allergens in adulthood, and each full-sibling cohort was first exposed to allergen either in puberty or at birth. All full-siblings had at least one allergic parent with an allergic phenotype, suggesting a predisposition to develop allergy. Allergen-specific IgE and IgG isotypes were measured before and after exposure toto determine whether maternal-acquired allergen-specific antibodies influenced the rate ofhypersensitivity development. All four cohorts were followed for at least nine years of allergen exposure. RESULTS: The rate of allergy development was inversely related to the timing of allergen exposure where introduction in adulthood led to the highest rate of allergy development (62.5%), a moderate allergy rate was found for introduction during adolescence (21.4%), and no individuals exposed at birth developedhypersensitivity. In addition, exposure to maternally-acquired allergen-specific IgE and IgG did not influence the rate of allergy development in the cohorts exposed to allergen at birth. DISCUSSION: We provide strong evidence in a full-sibling study that early-in-life allergen exposure, independent of maternal allergen-specific immunoglobulin, preventshypersensitivity development in individuals born to parents with an allergic phenotype.