Lintner T J, Eberhart R J
Department of Veterinary Science, College of Agriculture, Pennsylvania State University, University Park 16875.
Am J Vet Res. 1990 Apr;51(4):533-42.
The effects of 2 antibiotic preparations administered intramammarily on phagocyte recruitment, function, and morphology were evaluated at the beginning of the nonlactating period. Twelve cows with no clinical or microbiologic evidence of mastitis were assigned to 1 of 2 treatment groups. At the end of lactation, 1 of the antibiotic preparations was infused in a fore- and hind quarter of each cow; the remaining quarters were untreated controls. One group was given benzathine cephapirin; the second group was given sodium novobiocin. Secretion samples were collected from 1 treated and 1 control quarter at 16 hours, and from the remaining 2 quarters at 64 hours after treatment. Total and differential somatic cell counts were determined, and morphology of mammary polymorphonuclear neutrophils (PMN) and macrophages was observed by transmission electron microscopy. In vitro ingestion and killing of Staphylococcus aureus by mammary PMN and macrophages were assessed by fluorescent microscopy, using acridine orange stain. Cells resident in a fixed volume of secretion were incubated with a known concentration of S aureus. Total cell and PMN concentrations were higher in treated than in control quarters. Neutrophils were the predominant cell type in both treated and control quarters over the sampling period. As measured in this study, in vitro ingestion and killing of S aureus by individual PMN from treated quarters was reduced. Antibiotic treatment also increased the proportion of morphologically abnormal phagocytes. There were significant correlations among PMN ingestion, killing, and morphology. However, increased PMN concentrations tended to compensate for the reduced phagocytic function of individual cells. Therefore, efficacy of antibiotic treatment of nonlactating cows may depend, at least in part, on increased PMN concentration, which may tend to compensate for reduced phagocytic function. Compared with PMN, macrophages appeared to have only a minor role in phagocytosis of bacteria.
在非泌乳期开始时，评估了两种经乳房内给药的抗生素制剂对吞噬细胞募集、功能和形态的影响。将12头无乳腺炎临床或微生物学证据的奶牛分配到2个治疗组中的1组。泌乳期末，将其中一种抗生素制剂注入每头奶牛的一个前乳房和一个后乳房；其余乳房作为未处理的对照。一组给予苄星头孢匹林；第二组给予新生霉素钠。在治疗后16小时从1个处理过的乳房和1个对照乳房收集分泌样本，在64小时从其余2个乳房收集样本。测定了体细胞总数和分类计数，并通过透射电子显微镜观察了乳腺多形核中性粒细胞（PMN）和巨噬细胞的形态。使用吖啶橙染色，通过荧光显微镜评估乳腺PMN和巨噬细胞对金黄色葡萄球菌的体外摄取和杀伤。将固定体积分泌物中的细胞与已知浓度的金黄色葡萄球菌一起孵育。处理过的乳房中的总细胞和PMN浓度高于对照乳房。在采样期间，中性粒细胞是处理过的乳房和对照乳房中的主要细胞类型。在本研究中测定，来自处理过的乳房的单个PMN对金黄色葡萄球菌的体外摄取和杀伤减少。抗生素治疗还增加了形态异常吞噬细胞的比例。PMN摄取、杀伤和形态之间存在显著相关性。然而，PMN浓度的增加倾向于补偿单个细胞吞噬功能的降低。因此，非泌乳期奶牛抗生素治疗的疗效可能至少部分取决于PMN浓度的增加，这可能倾向于补偿吞噬功能的降低。与PMN相比，巨噬细胞在细菌吞噬中似乎只起次要作用。
