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Title: IN VITRO EXPRESSION OF ADHESION RECEPTORS AND DIAPEDESIS BY POLYMORPHONUCLEAR NEUTROPHILS DURING EXPERIMENTALLY INDUCED STREPTOCOCCUS UBERIS MASTITIS

Author
item SMITS, ELKE - UNIV OF GHENT
item BURVENICH, CHRISTIAN - UNIV OF GHENT
item Guidry, Albert
item ROETS, EDDY - UNIV OF GHENT

Submitted to: Infection and Immunity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/5/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Streptococcus uberis, a common bacteria found in the environment of the dairy cow, is responsible for 12 to 14% of the clinical cases of mastitis. Post-milking teat disinfection and antibiotic therapy, widely adopted in recent years, are relatively ineffective against S. uberis infection. It was shown that cows that had a more rapid influx of white blood cells (WBC) into the mammary following the introduction of bacteria were able to ward off infection more effectively. The current study used mammary secretory cells cultured as monolayers on porous membranes to study one of the major surface receptors responsible for migration of WBC from blood from the mammary gland. White blood cells from cows at various stages of S. uberis infection were studied for their ability to migrate through the monolayer. The relative ability of the cells to migrate was related to the surface receptor on WBC considered to be the primary factor in migration of WBC from the circulation to infected tissues. However, results showed migration of the WBC was associated with a decrease in these surface receptors. This suggests that in the bovine factors other than those normally active effect the movement of WBC from blood to the lumen of the mammary gland during S. uberis infection.

Technical Abstract: Expression of adhesion receptors and diapedesis by polymorphonuclear neutrophils were studied before and during experimentally induced Steptococcus uberis mastitis. Both quarters of the left udder half of five midlactation cows were inoculated with a suspension containing approximately 500 cfu of S. uberis strain 0140J. Clinical signs of an inflammatory reaction and leukocyte influx were observed 24 h after challenge. Expression of CD11b/CD18 adhesion receptors, determined by flow cytometry, was upregulated, 24 h after reaction. A confluent monolayer of bovine secretory mammary epithelial cells on collagen coated inserts was used to study neutrophil diapedesis. Bovine C5a was used as the chemoattractant. An 80% decrease in PMN diapedesis was observed 24 h after infection. The decrease in diapedesis continued for 3 weeks after infection.