Enzyme release by bovine neutrophils

Area of Science:

• Veterinary Immunology
• Cellular Biology
• Pathology

Background:

• Neutrophil-mediated tissue injury is linked to enzyme release from cytoplasmic granules.
• Understanding bovine neutrophil degranulation is crucial for pneumonic pasteurellosis research.

Purpose of the Study:

• To investigate the release of enzymes from primary granules, specific granules, and cytosol of bovine neutrophils.
• To compare enzyme release induced by chemical agonists versus Pasteurella haemolytica.

Main Methods:

• Quantified release of beta-glucuronidase (primary), B12-binding protein (specific), and lactate dehydrogenase (cytosolic).
• Stimulated neutrophils with phorbol myristate acetate, calcium ionophore, opsonized zymosan, and Pasteurella haemolytica (live/dead, opsonized/unopsonized).

Main Results:

• Live Pasteurella haemolytica induced the greatest release of all measured enzymes, partly due to neutrophil lysis.
• Bovine neutrophils selectively released specific granule contents in response to particulate agonists, enhanced by opsonization.
• Particulate agonists caused minimal primary granule release, except when cell death occurred.

Conclusions:

• Bovine neutrophils exhibit a marked, selective release of specific granules in response to Pasteurella haemolytica.
• The high degranulation rate, driven by abundant specific granules, likely contributes to tissue damage in pneumonic pasteurellosis.
• Opsonization significantly enhances the release of specific granule enzymes by bovine neutrophils when challenged with particulate pathogens.