Submitted to: Flemish Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/1997
Publication Date: N/A
Citation: N/A Interpretive Summary: Bovine neutrophils contain the enzyme acyloxyacly hydrolase (AOAH) that neutralizes endotoxin. We studied the activity of this enzyme in neutrophils isolated from lactating dairy cows. Between 10 and 26 d after parturition, activity of AOAH decreased 20% below prepartum values, and returned to prepartum values 2 mo after parturition. A decrease in phagocytosis and oxidative burst activity of neutrophils was also observed after parturi- tion. We suggest that decreased AOAH, phagocytic and oxidative burst activity of neutrophils shortly after parturition are factors that increase susceptibility of dairy cows to coliform mastitis during early lactation.
Technical Abstract: Neutrophils (PMN) play an important role in the inflammatory response of newly calved dairy cows to intramammary infections (IMI) with Escherichia coli and E, coli endotoxin (LPS) through phagocytosis, killing and LPS neutralizing activities. The role of PMN phagocytosis in mastitis is not completely understood. Decreased numbers of PMN and decreased phagocytic and respiratory burst activity of PMN predisposes cows to a severe inflammatory response to E. coli IMI. The severe systemic response of some cows to E. coli and E. coli LPS in the mammary gland has been attributed to an impairment of LPS detoxification. Detoxifica- tion by the PMN enzyme acyloxyacly hydrolase (AOAH) is an LPS neutralization mechanism that could play an important role in resistance of cows to E.coli IMI infections or E.coli LPS. The role of PMN phagocytosis and detoxification of LPS by AOAH needs to be clarified. Abstract