Department of Animal Sciences, Institute of Veterinary Medicine, Division of Microbiology and Animal Hygiene, Faculty of Agricultural Sciences, Georg-August-University Göttingen, Burckhardtweg 2, D-37077 Göttingen, Germany.
J Dairy Sci. 2011 Oct;94(10):5033-44. doi: 10.3168/jds.2011-4348.
Somatic cell counts (SCC) are generally used as an indicator of udder health. In Germany, a cutoff value of 100,000 cells/mL is currently used to differentiate between healthy and diseased mammary glands. In addition to SCC, differential cell counts (DCC) can be applied for a more detailed evaluation of the udder health status. The aim of this study was to differentiate immune cells in milk of udder quarters classified as healthy based on SCC values of <100,000 cells/mL. Twenty cows were selected and 65 healthy udder quarters were compared with a control group of 15 diseased udder quarters (SCC>100,000 cells/mL). Cells were isolated from milk of all quarters to measure simultaneously percentages of lymphocytes, macrophages, and polymorphonuclear neutrophilic leukocytes (PMNL) by flow cytometric analysis. The bacteriological status of all 80 quarters was also determined. Differential cell count patterns of milk samples (n = 15) with extreme low SCC values of ≤ 6,250 cells/mL revealed high lymphocyte proportions of up to 88%. Milk cell populations in samples (n = 42) with SCC values from >6,250 to ≤ 25,000 cells/mL were also dominated by lymphocytes, whereas DCC patterns of 6 out of 41 milk samples with SCC values from ≥ 9,000 to ≤ 46,000 cells/mL indicated already inflammatory reactions based on the predominance of PMNL (56-75%). In 13 of 15 milk samples of the diseased udder quarters (SCC >100,000 cells/mL), PMNL were categorically found as dominant cell population with proportions of ≥ 49%. Macrophages were the second predominant cell population in almost all samples tested in relation to lymphocytes and PMNL. Further analysis of the data demonstrated significant differences of the cellular components between udder quarters infected by major pathogens (e.g., Staphylococcus aureus; n = 5) and culture-negative udder quarters (n = 56). Even the percentages of immune cells in milk from quarters infected by minor pathogens (e.g., coagulase-negative staphylococci; n = 19) differed significantly from those in milk of culture-negative quarters. Our flow cytometric analysis of immune cells in milk of udder quarters classified as healthy by SCC <100,000 cells/mL revealed inflammatory reactions based on DCC.
体细胞计数（SCC）通常被用作乳房健康的指标。在德国，目前使用 100,000 个细胞/mL 的截止值来区分健康和患病的乳腺。除了 SCC 之外，还可以应用差异细胞计数（DCC）来更详细地评估乳房健康状况。本研究的目的是区分根据 SCC 值<100,000 个细胞/mL 分类为健康的乳房产区中的免疫细胞。选择了 20 头奶牛，并将 65 个健康乳房产区与 15 个患病乳房产区（SCC>100,000 个细胞/mL）的对照组进行比较。从所有乳房产区的牛奶中分离细胞，通过流式细胞分析同时测量淋巴细胞、巨噬细胞和多形核中性粒细胞（PMN）的百分比。还确定了所有 80 个乳房产区的细菌学状况。SCC 值极低（≤6,250 个细胞/mL）的 15 份牛奶样本的差异细胞计数模式显示高达 88%的高淋巴细胞比例。SCC 值为>6,250 至≤25,000 个细胞/mL 的 42 份样本的牛奶细胞群也主要由淋巴细胞组成，而 SCC 值为≥9,000 至≤46,000 个细胞/mL 的 41 份牛奶样本中的 6 份 DCC 模式表明基于 PMNL（56-75%）的优势，已经存在炎症反应。在 15 份患病乳房产区牛奶样本（SCC>100,000 个细胞/mL）中，有 13 份有规律地发现 PMNL 是主要细胞群体，比例≥49%。在与淋巴细胞和 PMNL 相关的几乎所有测试样本中，巨噬细胞是第二主要细胞群体。对主要病原体（例如金黄色葡萄球菌；n=5）感染的乳房产区和培养阴性乳房产区（n=56）的数据进行进一步分析表明，细胞成分存在显著差异。即使是由次要病原体（例如凝固酶阴性葡萄球菌；n=19）感染的乳房产区的免疫细胞百分比也与培养阴性的乳房产区有显著差异。我们通过 SCC<100,000 个细胞/mL 对分类为健康的乳房产区的牛奶中的免疫细胞进行流式细胞分析，发现基于 DCC 的炎症反应。
