engleski

Cell content in milk from cows with S. aureus intramammary infection

Somatic cell count, viability of cells and percentages of the cell subsets (CD45, granulocytes, monocytes/macrophages, CD4, CD8 and B lymphocytes) were determined in milk from uninfected cow udder quarters (n=7) and from quarters infected with S. aureus (n=18). Cell subpopulations were double labelled with monoclonal antibodies and determined by flow cytometry. Percentages of epithelial cells, polymorphonuclear granulocytes, monocytes and lymphocytes were determined by light microscopy in stained smears. The SCC, percentages of cells labelled with antibodies specific to CD45, granulocytes, CD4 and CD8 epitope were statistically different between infected and uninfected quarters. The percentages of cells obtained by light microscopy were statistically different between infected and uninfected group. The percentages of granulocytes in infected animals were associated with the age and gravidity of the animals. Within the infected group the percentage of CD8 statistically varied between imported replacement cows and animals raised on the farm. Values of epithelial cells and CD45- were moderately correlated (Pearson’s r=0.47). Percentages of granulocytes obtained by two methods were also moderately correlated (Pearson’s r=0.52).

milk; leukocytes; intrammamary infection; S. aureus

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