MedWire News: Researchers studying mice have found that airborne antigens can be transferred from mothers to neonates through breast milk, providing antigen-specific protection from allergic airway disease.

Allergic asthma results from an inappropriate T-helper type 2 response to environmental airborne antigens, and exposure to environmental antigens during infancy plays a crucial role in asthma development, the team explains.

Valérie Julia (Institut National de la Santé et de la Recherche Médicale, U924, France) and colleagues exposed mice to airborne ovalbumin (OVA) allergens while they were breastfeeding.

Offspring breastfed by mothers exposed to OVA had less airway hyperreactivity and allergen-induced lung pathology in response to OVA exposure than mice breastfed by non-exposed mothers.

The researchers report that airborne OVA was transferred from the mother to the newborn through the milk and presented to CD4+ T cells in the breastfed newborn. It was dependent on the presence of transforming growth factor (TGF)-beta during lactation.

"Breastfeeding-induced tolerance may rely on both the chronic administration of an antigen at low dose, a setting known to promote tolerance induction, and the presence of milk-borne TGF-beta," say Julia et al.

"This report gives new insights into the mechanisms underlying tolerance induction in neonates and pinpoints maternal influence through breast milk-mediated antigen transfer as a crucial factor in this process," they conclude.

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