Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/26/2004
Publication Date: 11/1/2004
Citation: Harp, J.A., Waters, T.E., Goff, J.P. 2004. Lymphocyte subsets and adhesion molecule expression in milk and blood of periparturient dairy cattle. Veterinary Immunology and Immunopathology. 102(1-2):9-17. Interpretive Summary: Mastitis (infection of the mammary gland) is a serious problem in dairy cattle that results in economic losses to producers of over 2 billion dollars annually in the U.S. In this study, we examined leukocytes (white cells that help control infections) in the blood and milk of cows after calving for the presence of adhesion molecules, proteins which allow the leukocytes to move from the blood into the milk. We found that leukocytes in the milk had a different array of these molecules compared with leukocytes in the blood. This suggests that a selected group of leukocytes move into the mammary gland around calving, and these may influence to degree to which cows are susceptible to mastitis. Understanding the process by which this occurs can lead to ways to better protect cows from mastitis, which will benefit the dairy industry worldwide.
Technical Abstract: Fifteen Holstein dairy cattle were monitored for lymphocyte subsets and expression of adhesion molecules on cells in milk and blood at parturition and at intervals up to 21 days postpartum. Using flow cytometry, we determined percentages of T cells (CD4+, CD8+, gamma/delta) and B cells from milk and blood of these cows. We also measured expression of adhesion molecules (CD62L, LFA-1, LPAM-1, and CD44) on lymphocytes in milk and blood. Significantly higher percentages of CD8+ cells were found in milk than in blood at all time points while significantly higher percentages of B cells were found in blood than in milk at all time points. There were minimal to no significant differences in percentages of CD4+ or gamma/delta+ cells between milk and blood. Expression of adhesion molecules was consistently higher on all subsets of milk lymphocytes compared with blood lymphocytes. These differences were most pronounced and statistically significant at calving and in the first week following calving. CD62L, LPAM-1 and CD44 were expressed on a significantly higher percentage of lymphocytes in milk at calving than in milk at subsequent sampling times, while LFA-1 expression on lymphocytes in milk was significantly lower at calving than at subsequent times.