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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Ruminant Diseases and Immunology Research » Research » Publications at this Location » Publication #76671
Title: PHENOTYPE ANALYSIS OF PERIPHERAL BLOOD MONONUCLEAR CELLS IN PERIPARTURIENT DAIRY COWS

Author
item KIMURA, KAYOKO - IA STATE UNIV., AMES, IA
item Goff, Jesse
item Kehrli Jr, Marcus
item Harp, James

Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/6/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Immediately around the time of calving, a cow's ability to fight off infections is reduced, making her susceptible to a variety of infectious diseases; the most important of which is infection of the udder, also called mastitis. We suspected that the white blood cells that comprise the immune system may be affected at the time of calving. We have developed techniques using antibodies directed against each of the different white blood cell types which allow us to quantify the percentage of each white blood cell type in blood samples. Blood samples were obtained from cows before and after calving to observe changes in the types of white blood cells present in the blood. We found that the total number of T-lymphocytic cells fell dramatically at calving and took about two weeks to recover their number. Most of this drop was due to a loss of T-helper, T-cytotoxic, and gamma-delta T-cells from the blood. The loss of these cells from the blood likely is key factor explaining why cows are immune suppressed at calving. As yet, we do not understand why these changes occur. However, if we can reverse these changes, perhaps we can reduce the susceptibility of dairy cows to diseases like mastitis.

Technical Abstract: Immune function is impaired in the periparturient cow. We suspect that changes in subpopulations of various peripheral blood mononuclear cell (PBMC) types might be occurring during the periparturient period. Using a flow cytometer and monoclonal antibodies (MAbs) directed against antigenic markers on mononuclear cells, the populations of total T-cells (Pan-T), T-helper, T-cytotoxic, gamma-delta-T-cells, interleukin 2 receptor (IL-2r), and major histocompatibility complex class II (MHC-II) Leukograms were also done to allow determination of absolute cell numbers. The percentage of cells positive for the Pan-T, T-helper, and gamma/delta-T-cell receptor markers exhibited a significant decline at calving and did not return to pre-calving levels until 2 weeks after calving. No significant changes were seen in other populations of cells. The decline in T-helper and gamma/delta-T-cell populations at calving may be responsible for the immunosuppression observed in dairy cows at calving. Why these population changes occur remains unknown.