Immunological Functions of the Mammary Gland and Its Secretion-Comparative Review

Abstract

The mammary gland performs vitally important immunological roles, both in providing passive immune protection to the suckling infant and in immunological defence of its own tissues against infection with microorganisms. These immunological functions differ greatly between species of mammals in both nature and magnitude. In ungulates the mammary gland is singularly responsible for transfer of immunoglobulin (IgG) from mother to young. This process is dependent on a highly selective mechanism which results in the transport of blood-borne IgG molecules across secretory epithelial cells of the colostrum-forming mammary gland and into secretion. Upon ingestion of colostrum by the young ungulate this immunoglobulin is absorbed across the wall of the small intestine and thence into the bloodstream.