Macromolecular absorption of food antigens in health and disease.

During the neonatal period, the development of the mucosal barrier against penetration of bacteria, toxins and antigens is an important protective mechanism against a variety of pathologic conditions such as inflammatory and allergic reactions. The closure of the gut with regard to the uptake of food antigens in macromolecular form is determined by non-immunologic mechanisms as well as by the immunologic system of the gut. Animal experiments show that various diseases affecting the gut may interfere with intestinal antigen handling. As a result, susceptibility to infection and allergic reactions may ensue. Studies performed in humans show that selective IgA deficiency, preterm delivery, intestinal helminth infection and type of feeding during the neonatal period may influence antigen uptake by the intestinal epithelium. These conditions, as well as various diseases affecting the gut, may cause increased absorption of intraluminal antigens and result in the triggering of allergic type responses.