Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2003
Publication Date: 3/1/2004
Citation: Harp, J.A., Stabel, J.R., Pesch, B.A., Goff, J.P. 2004. Expression of adhesion molecules on milk and blood leukocytes from periparturient dairy cattle with Johne's disease. Veterinary Immunology and Immunopathology. 98(1-2):69-76. Interpretive Summary: Johne's disease (bovine paratuberculosis) is a serious bacterial infection of cattle that results in gradual loss of condition and eventual death. As many as 20-40% of dairy cattle herds and up to 8% of beef cattle herds in the United States are thought to be infected. Chronic infection in cattle can be worsened by the stress of calving, and increased numbers of bacteria may be shed in milk and other secretions, increasing the risk of transmission to other animals in the herd. In this study, we examined leukocytes (white cells that help control bacterial infections) in the blood and milk of cows infected with Johne's disease 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 to 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 shed the Johne's bacteria into the milk. Understanding the process by which this occurs can lead to ways to better protect cows from recrudescence of Johne's disease around the time of calving, as well as controlling acute infections such as mastitis. These studies will greatly benefit the dairy and beef industry worldwide.
Technical Abstract: Twelve dairy cows infected with Mycobacterium avium subsp. paratuberculosis were monitored for leukocyte subsets and expression of adhesion molecules on cells in blood and milk during the 3 weeks before and 3 weeks after calving. Six cows were fed a control diet ad libitum and 6 cows received additional feed to improve their energy balance during the periparturient period. Using fluorescent antibody labeling of cells and analysis by flow cytometry, we examined expression of the adhesion molecules CD62L, CD11a, alpha4-beta7 and CD44 on T cell subsets (CD4+, CD8+, gamma/delta+) and neutrophils from blood and milk of these cows. Providing additional energy had no effect on the parameters reported herein. CD62L was expressed on 50-80% of the various T cell subsets in blood and 70-99% in milk from 0 to 21 days after parturition. Nearly all neutrophils in blood expressed CD62L compared with 70-80% in milk. CD11a was found on 10-40% of T cells in blood, and 30-80% in milk. Nearly all neutrophils in blood expressed CD11a compared with 60-80% in milk. Alpha4-beta7 was expressed on 10-30% of T cells in blood and 80-99% in milk. Ten to 25% of neutrophils in blood expressed alpha4-beta7, and 60-70% in milk. CD44 was expressed on 70-99% of T cells from both blood and milk. Nearly all neutrophils in blood expressed CD44 compared with 40-60% in milk. Differences in some of these data compared with previously reported values for non-infected cows suggest that chronic infection with M. avium subsp. paratuberculosis may affect lymphocyte subset and adhesion molecule expression in the bovine. In addition, differences in the percents of leukocytes expressing adhesion molecules in milk compared to blood suggest that these cells are selectively recruited to mammary gland from the circulation.