Antigen absorption from the small intestine and gastrointestinal disease.

In this article, I have attempted to summarize the concept of intestinal permeability to antigens such as ingested food proteins, bacterial breakdown products, endotoxins, and enzymes. The mature gut retains the capacity to absorb macromolecules by a pinocytotic mechanism which is more pronounced during the neonatal period. The vast majority of individuals have no ill effects from the intestinal transport of large molecules. However, when increased quantities of toxic or antigenic macromolecules gain access to the body because of a derangement in the intraluminal digestive process or because of a defect in the mucosal barrier, antigen absorption may be altered and result in either local intestinal or systemic disorders. The speculative concepts suggesting that clinical disease states may be associated with altered mucosal permeability have been discussed.