Antigen handling by the small intestine

In this review, I have attempted to summarize the research done in a poorly understood area of gastroenterology, namely the role of the intestine in handling luminal antigens. The mature gut retains the capacity to absorb antigens by an energy-dependent, pinocytotic mechanism similar to that described for the transport of gamma-globulins in certain mammalian species in the neonatal state. The vast majority of adults show no ill effects as a result of this physiological phenomenon due to mucosal barrier function. However, when the barrier is disrupted and increased (pathological) quantities of toxic or antigenic macromolecules gain access to the body because of a derangement in the intraluminal digestive process or a defect in the mucosal barrier, antigen handling may be altered and result in either local intestinal or systemic disease. Finally, speculative concepts suggesting that clinical disease states may be associated with altered mucosal permeability have been discussed.