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

The expression of adhesion receptors and diapedesis by polymorphonucle ar neutrophils (PMN) were studied before and during experimentally ind uced Streptococcus uberis mastitis. Both quarters of the left half of the udders of five midlactation cows were inoculated with a suspension containing approximately 500 CFU of S. uberis 0140J. Clinical signs o f an inflammatory reaction and leukocyte influx were observed 24 h aft er challenge. The expression of CD11b/CD18 adhesion receptors, determi ned by flow cytometry, was upregulated 24 h after challenge. A conflue nt monolayer of bovine secretory mammary epithelial cells on collagen- coated inserts was used to study PMN diapedesis. Bovine C5a was used a s the chemoattractant. An 80% decrease in PMN diapedesis was observed 24 h after challenge. The decrease in diapedesis continued for 3 weeks after challenge.