Alteration of neutrophil function associated with coccidiosis in cattle: influence of decoquinate and dexamethasone.
Twenty Holstein steers subclinically infected with coccidia were allotted to 2 groups of 10 steers each. One group received a diet containing 0.5 mg of decoquinate/kg of body weight. After 25 days on the diet, there was no difference between the groups in lymphocyte blastogenic responsiveness to mitogens; however, there were differences in neutrophil function. Lymphocytes from steers of the decoquinate-fed group had decreased random migration under agarose, enhanced cytochrome C reduction, and enhanced iodination activity. Other measures of neutrophil function evaluated (chemotactic index, Staphylococcus aureus ingestion, and antibody-dependent and -independent cell-mediated cytotoxicity) were not affected. After 30 days of decoquinate feeding, half of the cattle in each group received 5 daily IM injections of dexamethasone (0.04 mg/kg of body weight). The dexamethasone-treated steers from the group that did not have decoquinate in the diet developed clinical coccidiosis, whereas the decoquinate-treated steers remained clinically normal. Lymphocyte and neutrophil function were again evaluated for a 3-day period beginning 4 days after dexamethasone treatment was halted. Neutrophils from the steers that developed clinical coccidiosis after dexamethasone administration had significantly (P less than 0.05) inhibited random migration under agarose, cytochrome C reduction, and iodination activity, but significantly (P less than 0.01) enhanced S aureus ingestion. The feeding of decoquinate prevented the inhibition of neutrophil cytochrome C reduction and lessened the inhibition of neutrophil iodination in the dexamethasone-treated group. Dexamethasone treatment was associated with an inhibition of lymphocyte blastogenic responsiveness to phytohemagglutinin in principals as well as controls.
Roth
J A
JA
Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames 50011.
Jarvinen
J A
JA
Frank
D E
DE
Fox
J E
JE
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology*; D002634:Chemotaxis, Leukocyte / Q000187:drug effects; D003048:Coccidiosis / Q000276:immunology / Q000662:veterinary*; D003667:Decoquinate / Q000494:pharmacology*; D003907:Dexamethasone / Q000494:pharmacology*; D006912:Hydroxyquinolines / Q000494:pharmacology*; D007958:Leukocyte Count / Q000662:veterinary; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D009504:Neutrophils / Q000276:immunology / Q000502:physiology*; D010587:Phagocytosis
D006912:Hydroxyquinolines; D003667:Decoquinate; D003907:Dexamethasone