Development of intestinal host defense mechanisms and the passive protective role of human milk.

In this review of development of host defense mechanisms of the gastrointestinal tract, I have attempted to develop the concept of a mucosal barrier to the uptake of intestinal antigens and microorganisms. Alterations in development of immunologic defense and non-immunologic defenses results in an increased vulnerability for clinical disease in the newborn (premature) infant. The passive role of human milk in promoting intestinal maturation and protecting the newborn gut from pathologic penetration of macromolecules is discussed. It was predicted that many, as yet undiscovered factors, will be reported in future years to further underscore the importance of human milk in perinatal host defense. Immediate and delayed disease states resulting from an altered defense were considered.