Plasmablast recruitment to the ruminant mammary gland

Antibodies in milk have the potential to protect humans against disease caused by gut pathogens such as rotavirus, enterotoxic 'E.coli' and 'Vibrio cholerae', which are major causes of human death worldwide. Consumption of ruminant milk products containing specific antibodies against the causative agents of such diseases can significantly reduce their prevalence and severity. During colostrogenesis, large quantities of IgG1 are selectively transported across the mammary epithelium into the ruminant mammary gland producing antibody rich colostrum and providing passive immunity to the neonate. An influx of antibodies into the mammary gland can also be detected in response to inflammation during involution. However, at the commencement of lactation, IgG1 transport is down-regulated, dramatically reducing antibody concentrations in milk. During this phase of the lactation cycle, plasma cells located within mammary tissues are thought to be the main source of antibodies in milk. An understanding of the mechanism by which plasmablasts are recruited to the mammary gland could create opportunities to manipulate this process. Migration of plasma blasts is thought to be dependent upon their response to a series of adhesive and migration signals provided by chemokines and vascular adhesion molecules. To investigate the expression of these candidate chemokine and vascular adhesion molecules at various stages of the lactation cycle, secretory tissue was collected from the ovine mammary glands of ewes 2 weeks pre- and 2 and 4 weeks post- lambing. Ovine transcripts for CCL25, CCL28, CXCL10, MAdCAM-1, VCAM and GlyCAM have been cloned and primers designed for their quantification by real-time PCR relative to reference genes. Data on relative expression levels will be presented.