Effects and Significance of the Mammary Environment on Bovine Neutrophil Function
Didier, Peter J.
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https://hdl.handle.net/2142/71350
Description
Title
Effects and Significance of the Mammary Environment on Bovine Neutrophil Function
Author(s)
Didier, Peter J.
Issue Date
1988
Doctoral Committee Chair(s)
Shadduck, John A.
Department of Study
Veterinary Medical Science
Discipline
Veterinary Medical Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Agriculture, Animal Pathology
Abstract
Bovine neutrophils separated from the circulation (bPMN) and from milk (mPMN) of inflamed mammary glands (inoculated with oyster glycogen) were compared for expression of C3 and Fc surface receptors (CR and FcR), and for metabolic, phagocytic, and chemotactic function. This study characterized receptor expression by rosette methods, measured metabolism by nitroblue tetrazolium reduction and glycolysis, and phagocytosis and killing of Staphylococcus aureus and Saccharomyces cerevisiae by microscopic exam, flow cytometry, and microbiologic culture. Chemotaxis was measured by under agarose assay. An improved method of bPMN separation was developed.
In experiments with nine cows, CR expression in mPMN decreased from 66.2 $\pm$ 1.7% on Day 1 to 27.3 $\pm$ 2.8% on Day 3 following initiation of mammary inflammation. There was no change in CR expression of bPMN and in FcR expression of bPMN and mPMN during the three days. Metabolic response decreased in mPMN with time but phagocytic and killing capacity for both organisms was similar for mPMN and bPMN. Chemotaxis of mPMN was substantially decreased at all time points. Viability of mPMN decreased to 85% based on trypan blue exclusion and to 55% based on uptake of fluorescein diacetate.
In other in vitro experiments exposure of bPMN to normal cream, whey, unstimulated endothelial monolayers, phospholipase, neuraminidase, and papain failed to alter receptor expression. However, trypsin, oxygen free radicals, and culture-conditions (for three days) decreased CR but not FcR expression. The depression of CR in cultured bPMN could not be enhanced with cultured macrophage-supernatants. Lectin-staining showed similarities between mPMN and cultured bPMN. Inflammatory cells and supernatants from milk did not decrease CR expression of bPMN. Milk supernatants nonspecifically enhanced CR expression in Day 1 mPMN. Only Day 1 supernatant enhanced CR expression of bPMN. In conclusion decreased CR expression of mPMN was related to time spent outside the circulation. Phagocytosis and killing were not compromised. Activity of exogenous or endogenous trypsin-like enzymes and free radical oxygen may be the mechanisms of this depression that produces an absolute decrease in molecules of CR detected in surface membranes of aging mPMN.
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