Breast-feeding and its role in early development of the immune system in infants: Consequences for health later in life

Because of the interaction between mother and child during pregnancy, excessive and destructive inflammatory responses must be avoided during the development of the fetus. Active inhibition of the immune system of the fetus to inhibit "immune abortions" results in an immature immune system at birth and during the first years of life, making the child susceptible to infections and immune disorders. The development of the immune system in infants is characterized by the induction of an antigen-specific immune response and maintenance of immunological tolerance against commonly found compounds in the environment of the infant. Improper immune maturation may lead to lifetime immunological disorders such as allergic disorders and autoimmunity. The interaction between mother and child postpartum plays an important role in the development of the infant's immune system. The immunological memory of the mother is passed to her infant via breast milk, and breast milk contains a variety of immune-modulating compounds causing immunological imprinting and programming (88). This review clearly illustrates that knowledge of the development of the immune system in infants has numerous black holes. Investigations on the interplay between mother and child after birth, including studies of the content of breast milk, are needed to support the described concepts. Because the active downregulation of the immune system during pregnancy and infancy shows similarities with immunological tolerance in later life (2), the investigations will not only fulfill our academic curiosity but will also lead to new targets and therapeutics to prevent and/or inhibit allergies and autoimmune diseases. © 2008 American Society for Nutrition.