Breast feeding may help protect babies against allergic asthma. Airborne allergen is able to pass from mother to child through breast milk, which cre

Allergic asthma affects 300 million people worldwide and is characterized by obstruction of the respiratory pathways in response to allergen exposure. Its prevalence has increased in recent decades, probably due to changes in environmental factors. Indeed, exposure to environmental antigens during infancy reduces the likelihood of developing asthma.

Valerie Julia and her colleagues investigated whether exposing lactating mice to an airborne allergen — ovalbumin — affected asthma development in the offspring. They found that ovalbumin was efficiently transferred from the mother to the neonate through the milk, leading to the development of immunological tolerance. Tolerance induction relied on the presence of transforming growth factor–beta and was mediated by regulatory CD4+ T lymphocytes, but did not require the transfer of immunoglobulins through the milk.

Breast milk–mediated transfer of an antigen to the neonate can result in oral tolerance induction, leading to antigen-specific protection from allergic asthma. These observations may pave the way for the design of new strategies to prevent the development of allergic diseases.