The Mammary Gland Immune Response and Its Relationship to Intestinal Antigenic Exposure

Human milk contains antibodies of the secretory IgA (SIgA) type directed against a variety of enterobacteria, viruses and food proteins. The appearance of these milk antibodies with specificity against antigens of intestinal origin is difficult to explain, unless there is a close link between the immune response in the mammary gland and intestinal exposure. There is some evidence which suggests that antigens in the intestine may stimulate lymphoid cells from the Peyer’s patches which are committed to IgA synthesis to home to various exocrine glands, including the mammary gland. As a consequence of the enteromammaric Zink, the breast-fed baby is supplied with SIgA milk antibodies against micro-organisms which are common in the environment. These antibodies have the capacity to prevent bacterial attachment to mucous membranes which is the initial step in most infections. Determination of milk antibodies also provides epidemiological information concerning intestinal pathogens and can be used to reflect mucosal immunity in response to various vaccinations.