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.In other species, including rodents and primates, there is a well-developed local IgA system operating in the mammary gland. In this situation, plasma cells located near the basal membranes of secretory epithelial cells secrete IgA which passes through the epithelial cells and into colostrum or milk. In these species the IgA in mammary secretions is not absorbed into the circulation of the suckling infant; because of its unique property of resisting proteolytic degradation, it may mediate a local protective role in the lumen of the intestine of the suckling infant.Specific immunological protection of mammary tissue may be mediated through blood-derived antibody (particularly IgG), locally synthesized antibody (particularly IgA) or phagocytic cells. Neutrophils arrive in mammary tissue and secretions in very large numbers following bacterial invasion of the gland. It has been established recently that these cells carry cytophilic antibody on their cell membrane. This cytophilic antibody can play an important functional role in enhancing the phagocytic capacity of neutrophils in the mammary gland.

Effects of phytogenic substances on growth performance, digestibility of nutrients, faecal noxious gas content, blood and milk characteristics and reproduction in sows and litter performance

“…In the 6th week prior to parturition, colostrogenesis has begun. Antibodies found in the initial lacteal secretions partly (IgA) or solely (IgG) originate from the sows circulation (Watson, 1980) and a boost to serum antibodies during this period would therefore be thought to lead to an improvement in colostrum levels. Also, Mauch and Bilkei (2004) reported that essential oils (oregano) decreased populations of undesirable microorganisms and stimulated the secretion of antibodies maybe positively infl uenced IgG and IgA level in colostrum.…”

Cloning and Characterization of the Bovine MHC Class I-Like Fc Receptor

“…Upon ingestion of the colostrum, Igs are transported across the intestinal barrier of the neonate into its blood. Whereas this intestinal passage appears to be somewhat nonspecific for types of Igs, there is a high selectivity in the passage of these proteins from the maternal plasma across the mammary barrier into the colostrum (2)(3)(4)(5), and only IgG1 is transferred in large amounts (6). There is a rapid drop in the concentration of all lacteal Igs immediately postpartum (7), and the selectivity of this transfer has led to the speculation that a specific transport mechanism across the mammary epithelial cell barrier is involved.…”

Transferência de imunidade passiva em bezerras alimentadas com colostro de vacas com mastite subclínica

“…O aumento dos valores de PT, globulinas e frações eletroforéticas após a ingestão do colostro é consensual e ocorre pela passagem de imunoglobulinas provenientes do colostro pelo epitélio intestinal do bovino recém-nascido nas primeiras 24 horas de vida (WATSON, 1980). Os valores obtidos nesta pesquisa, nas provas bioquímicas, foram semelhantes aos encontrados por FEITOSA et al (2001) para proteína total (6,55 g/dL) e albumina (2,61 g/dL) após a ingestão do colostro, porém a atividade sérica da enzima GGT foi menor do que aquela relatada pelo último autor citado (702,45 U/L).…”

“…O colostro bovino contém elementos solúveis e celulares biologicamente ativos, sendo a IgG1 o principal componente imune transferido da circulação para a glândula mamária pelo mecanismo seletivo denominado de colostrogênese (WATSON, 1980). Essa imunoglobulina protege os bezerros especialmente pela sua capacidade de opsonização, neutralização e intensificação do mecanismo de citotoxicidade celular dependente de anticorpos (BIBURGER et al, 2014).…”