H. Dosogne et al., REDUCTION OF ACYLOXYACYL HYDROLASE ACTIVITY IN CIRCULATING NEUTROPHILS FROM COWS AFTER PARTURITION, Journal of dairy science, 81(3), 1998, pp. 672-677
Bovine neutrophils contain the enzyme acyloxyacyl hydrolase, which hyd
rolyzes the acyloxyacyl linkage of the two nonhydroxylated fatty acyl
chains to two 3-hydroxy fatty acids in the highly conserved lipid A pa
rt of endotoxins with high specificity. This hydrolysis decreases the
toxicity of lipid A, but the immunostimulatory capacity of endotoxins
is largely maintained. In two trials, we studied the activity of acylo
xyacyl hydrolase in neutrophils that had been isolated from the blood
of 18 dairy cows around parturition. Between 10 and 26 d after parturi
tion, the activity of acyloxyacyl hydrolase in neutrophils decreased a
pproximately 20% below prepartum activity. At about 2 mo after parturi
tion, acyloxyacyl hydrolase activity returned to prepartum values. Cha
nges in acyloxyacyl hydrolase activity could not be attributed to chan
ges in binding of lipopolysaccharides by the CD14 molecules on neutrop
hils or monocytes. We hypothesize that decreased acyloxyacyl hydrolase
activity in neutrophils shortly after parturition is a factor that in
creases the susceptibility of dairy cows to coliform mastitis during e
arly lactation.