ENTEROMAMMARY IMMUNE SYSTEM - IMPORTANT NEW CONCEPT IN BREAST-MILK HOST DEFENSE

The discovery that secretory IgA was the predominant immunoglobulin in external secretions stimulated a great deal of research into the secretory immune system and in particular into the relationship between oral immunization and the appearance of antibody at distant epithelial sites such as in the oral cavity and breast. It has become clear that there is a continuous traffic of plasma cells between the gut-associated lymphatic tissue into the systemic circulation and then back to the gut to provide local secretory immunity and also to distant sites again to provide the same specific immunity. Most often the effects of immunization within the system are not reflected in the serum. Deficiencies in this system of external protection are reflected in increased incidences of autoimmune diseases, allergy, diarrheal disease, and cancer in those people with absent secretory IgA. With better understanding of those pathways involved in homing and induction of SIgA, such as the function of hormonal influences on the population of the breast glandular epithelium, the diapedesis of cells from the breast into the colostrum, and the influences of T cells and macrophages presented to the newborn in the colostrum, it may be possible to influence the course of inherited or acquired diseases whose pathogenesis is influenced by decreased enteric immunity. We now also have the possibility of using the passive immunity given by breast milk to protect infants against a number of infectious diseases and toxins to which they are particularly vulnerable, such as neonatal meningitis and food allergy. © 1979 Digestive Disease Systems, Inc.