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.
Department of Veterinary Microbiology, College of Veterinary Medicine, Iowa State University, Ames 50011.
J A
JA
Roth
J A
JA
Jarvinen
D E
DE
Frank
J E
JE
Fox
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