Search Results

You are looking at 1 - 2 of 2 items for

  • Author or Editor: Araceli Diez-Fraile x
  • Refine by Access: Content accessible to me x
Clear All Modify Search

Abstract

Objective—To determine whether proinflammatory mediators and glucocorticoids affect CD62L(L-selectin) expression on peripheral blood neutrophils from cows in various stages of lactation.

Animals—100 healthy dairy cows during early (13.1 ± 0.79 days after parturition; n = 31), peak (58.7 ± 1.64 days after parturition; 31), and mid (137.2 ± 2.59 days after parturition; 38) lactation.

Procedure—In vitro effects of relevant proinflammatory mediators that are released in response to mastitis caused by gram-negative bacteria such as lipopolysaccharide (endotoxin), tumor necrosis factor-α, and platelet-activating factor (PAF) on CD62L expression on bovine neutrophils were assessed by flow cytometry. Influences of cortisol and dexamethasone on CD62L expression on bovine neutrophils were also investigated.

Results—Basal CD62L expression on neutrophils from cows during early, peak, and mid lactation were similar. Lipopolysaccharide and tumor necrosis factor-α had no effect on CD62L expression on neutrophils from cows at any stage of lactation. Conversely, PAF elicited a time- and dose-dependent, down regulatory effect on CD62L expression. However, no differential shedding of CD62L from neutrophils of cows at any stage of lactation were detected. In addition, no effects on CD62L expression on bovine neutrophils after whole blood incubation with cortisol or dexamethasone were observed. Incubation with glucocorticoids did not prevent the down regulatory effect of PAF on CD62L expression.

Conclusions and Clinical Relevance—Comparable basal CD62L expression on bovine neutrophils and equal amounts of CD62L shedding from bovine neutrophils during all stages of lactation suggest that variations in CD62L density are not a likely cause of susceptibility of cows to coliform-induced mastitis during early lactation. (Am J Vet Res 2004;225:1421–1426)

Full access
in American Journal of Veterinary Research

Abstract

Objective

To determine the effect of mastitis caused by Escherichia coli on expression of CD18 cell surface receptors and to evaluate the involvement and regulation of receptors by lipopolysaccharide (LPS) and cortisol.

Animals

11 clinically normal lactating Holstein-Friesian cows.

Procedure

Binding of CD18 monoclonal antibodies to neutrophils was studied, using flow cytometry, before and after intramammary inoculation of E coli organisms. Effect of LPS and cortisol on expression of adhesion receptors was investigated, using a whole-blood model.

Results

Expression of CD18 adhesion receptors on bovine neutrophils increased 35% by 12 hours after intramammary inoculation of E coli. By 24 hours after inoculation, the number of receptors had returned to control values. High cortisol concentrations (100 nmol/L) were seen 12 to 18 hours after inoculation. Addition of LPS to blood induced a 30% increase in the number of CD18 receptors, and maximal number of receptors was expressed at an LPS concentration of 0.1 ng/ml. A decrease in the number of CD18 receptors was induced by incubation with cortisol or dexamethasone before challenge-exposure with LPS.

Conclusions

An increase in the number of CD18 receptors on neutrophils is mediated by local production of LPS. Subsequent endogenous release of cortisol may prevent additional increases in the number of receptors.

Clinical Relevance

During acute mastitis caused by E coli, there is an increase in the number of CD18 receptors on circulating neutrophils. Cortisol induces a decrease in the number of CD18 receptors, probably modulating the acute inflammatory response in mammary glands of lactating cows. (Am J Vet Res 1999;60:534–540)

Free access
in American Journal of Veterinary Research