Lung microbiota promotes tolerance to allergens in neonates via PD-L1

The immune system matures during the neonatal period and is influenced by environmental factors. Benjamin J. Marsland and his colleagues show that the lung is colonized by microbes early in life. Formation of the lung microbiota is associated with the induction of regulatory T cells and the development of tolerance to allergens. Absence of microbial colonization leads to allergic airway disease later in life, suggesting that the lung microbiota promotes immune tolerance.