DEFENSE FACTORS IN HUMAN-MILK

The newborn infant is more susceptible to infections than older children or adults. This is because all three lines of defense against microbial invasion, ie, barrier functions, innate immunity, and specific immunity, are to a greater or lesser extent immature at birth. Nature's response to the immaturity of the infant's immune system is to provide ready-made defense factors from the mother. This is achieved first by the transplacental passage of IgG antibodies, and later via the breast milk. Breastfeeding has been shown to decrease morbidity in gastroenteritis, septicemia, otitis media, urinary tract infection, and necrotizing enterocolitis. Breast milk contains a wide variety of defense factors, ie, immunoglobulins, leukocytes, hormones, cytokines, and complex oligosaccharides in free form or bound to macromolecules. These factors are reviewed and their potential protective effects in the abovementioned clinical states are discussed.