Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/25/2001
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Four multiparous lactating cows were used in 4x4 Latin square design to assess effects of LPS (serotype E. coli O11:B4 at 0.0, 0.5, 1.0, 1.5 ug/kg BW) on blood leukocyte populations, cytokines (TNF-alpha and IFN-gamma) and vitamins [retinol, RRR-alpha-tocopherol and beta-carotene (provitamin A)]. LPS, in 100 ml of sterile physiological saline, was infused IV at 1 ml/min over 100 min. Blood was collected by jugular catheter immediately before infusion (0 h) and at 2 (leukocytes not sampled at this time), 4, 6, 24 and 48 h. Samples were shipped overnight to the NADC for analysis. Blood leukocytes were phenotyped by flow cytometry and the cytokines and vitamins were quantified by an ELISA and reverse-phase HPLC. LPS infusion caused a marked leukopenia at 4 and 6 h that was characterized by a reduction in the number of T cells (CD3+, CD4+, CD8+ and gamma/delta TCR+ subsets), B cells, monocytes and cells expressing IL-2 receptors and MHC class II antigens. By 24 h, values were comparable to preinfusion and control-cow values. Percentages of B cells and gamma/delta-TCR+, IL-2r+ and MHC class II antigen+ cells in leukocyte populations from LPS-treated cows were elevated at 4 and 6 h. Serum TNF-alpha was affected by infusion of LPS in a dose-dependent fashion, with maximal concentrations occurring at 2 h. TNF-alpha concentrations declined precipitously from 2-6 h and were not different from preinfusion values or those of control cows at 24 h. Serum IFN-gamma, extremely low throughout the experimental period, was unaffected by LPS. Plasma retinol, RRR-alpha-tocopherol, and beta- carotene also were unaffected by LPS. These results and metabolic data presented previously suggest LPS-induced inflammation influences broad aspects of the immune system, affecting the metabolism of dairy cows.