Diapedesis, phagocytosis and microbicidal activity are important parameters of neutrophil functionality and thus outcome of mastitis. An in vitro model of an "alveolar pavement" using the MAC-T3 bovine mammary epithelial cell line was developed to assess neutrophil diapedesis. Features of this biologically-meaningful barrier include: characteristic transepithelial resistance, tight junction complexes and polarity. Continuous transepithelial resistance measurements showed no significant changes throughout the assay period. Neither a Staphylococcus aureus challenge ($1 times10 sp7$ and $2 times10 sp9$ cfu/ml), or the presence of neutrophils, both resting and challenged had any deleterious effects on monolayer integrity over a short term (1-2 h) exposure. Neutrophils, both resting and challenged gave no indication of causing damage to the epithelium over the short term. Neutrophils isolated from proven sires and evaluated for phagocytic activity were found to differ significantly (p $<$ 0.05) in activity, rate and capacity to uptake particles. Correlations between phagocytic parameters and production traits were negative and small in magnitude. Microbicidal activity of neutrophils isolated from proven sires showed a highly significant variation between animals due to test day (p $<$ 0.001), however variation due to source of cells (i.e. animal) was not significant. in vitro analysis of diapedesis and phagocytosis is promising as a tool for the assessment of resistance or susceptibility to mastitis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68211 |
| Date | January 1994 |
| Creators | Macdonald, Elizabeth A. |
| Contributors | Turner, J. D. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Animal Science.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001396103, proquestno: AAIMM94469, Theses scanned by UMI/ProQuest. |
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