Breast Milk Immunology

There has recently been renewed interest in the unique protective properties of breast milk. A part of this interest has focused on the immunocompetent cellular components and has followed the reports of colostrum halting otherwise uncontrollable epidemics of newbornEscherichia colidiarrhea1,2and its content of specific substances that neutralize both cholera andE colienterotoxin.3,4The specific antitoxin seems to be secretory IgA (SIgA), which is the only immunoglobulin synthesized in vitro by human milk B-lymphocytes.5,6Additional interest in breast milk has been generated by the observation that colostral feeds stimulate growth and maturation of intestinal mucosa in beagle puppies7and that higher concentrations of SIgA develop in breast-fed infants in their salivary and nasal secretions in the first four days of life than do bottle-fed infants.8Thus, the complex interactions of breast milk constituents resulting in the immunoprotection, development, and maturation of the