ABSTRACT

One of the most important concepts in the area of immune defenses at mucosal surfaces is that antigenic information presented to one mucosal surface in an organism or an individual can be shared by other mucosal surfaces. The predominant immunoglobulin in colostrum is IgA. It is present both as a dimer complexed with the glycoprotein known as secretory component and as the free monomer. The total IgA content of colostrum is about ten times the IgA content of serum. The specificities of the colostral antibodies reflect maternal enteral antigenic experience. In female rabbits, the feeding of dinitrophenylated antigens induced specific secretory IgA in breast milk. The final limb of the enteromammary pathway is the delivery of colostrum and its immunoactive substances to the infant's intestine. There is much evidence to suggest that these substances remain active after reaching the infant's gut.