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


METHODS
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.


METHODS
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-alpha, 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-alpha 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
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.
Diez-Fraile
Araceli
A
Department of Physiology, Biochemistry and Biometrics, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820 Merelbeke, Belgium.
Meyer
Evelyne
E
Duchateau
Luc
L
Burvenich
Christian
C
D000818:Animals; D002417:Cattle / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D005434:Flow Cytometry / Q000662:veterinary; D005455:Fluorescent Antibody Technique / Q000662:veterinary; D005938:Glucocorticoids / Q000494:pharmacology*; D006854:Hydrocortisone / Q000494:pharmacology; D018836:Inflammation Mediators / Q000494:pharmacology*; D019041:L-Selectin / Q000378:metabolism*; D007774:Lactation / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D010972:Platelet Activating Factor / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D005938:Glucocorticoids; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D010972:Platelet Activating Factor; D014409:Tumor Necrosis Factor-alpha; D019041:L-Selectin; D003907:Dexamethasone; D006854:Hydrocortisone