title: Induction of the acute-phase cytokine, hepatocyte-stimulating factor/interleukin 6, in the circulation of horses treated with endotoxin.
abstract: Because hepatocyte-stimulating factor/interleukin 6 (IL-6) is the principal inducer of acute-phase protein synthesis in the liver, quantification of its activity in blood provides an early and sensitive assessment of the acute-phase response. Circulating IL-6 activity was monitored in 4 adult horses for 72 hours after IV administration of endotoxin. In 4 experiments performed at weekly intervals and in randomized order, each horse was given endotoxin--1,000 30, 1, and 0 ng/kg of body weight. Plasma IL-6 activity was quantified as the ability to promote growth of the IL-6-dependent B-cell hybridoma, B13.29 clone B9. Interleukin-6 activity (171 +/- 10.2 U/ml) was found in all pretreatment plasma samples and was significantly (P less than 0.05) increased above baseline from 2 to 12 hours after 1,000 ng of endotoxin/kg was given and at 3 hours after 30 ng of endotoxin/kg was given. After 1,000- or 30-ng/kgt dosage of endotoxin, peak plasma IL-6 activity (10,128 +/- 4,096 and 1,555 +/- 1,326 U/ml, respectively) was observed for 3 hours. The IL-6 response of endotoxin-treated horses began about 1 hour after tumor necrosis factor appeared in the circulation, and its course closely approximated the endotoxin-induced febrile reaction. Significant increase in plasma IL-6 activity was not detected in horses given 1 ng of endotoxin/kg or control buffer.
authors.affiliation: Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville 32610.
authors.forename: R J
authors.initials: RJ
authors.lastname: MacKay
authors.forename: G D
authors.initials: GD
authors.lastname: Lester
mesh_terms: D000210:Acute-Phase Reaction / Q000097:blood / Q000662:veterinary*; D000818:Animals; D001831:Body Temperature / Q000187:drug effects; D004731:Endotoxins / Q000494:pharmacology*; D004926:Escherichia coli; D006339:Heart Rate / Q000187:drug effects; D006734:Horse Diseases / Q000097:blood*; D006736:Horses; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000097:blood; D007958:Leukocyte Count / Q000187:drug effects / Q000662:veterinary; D008070:Lipopolysaccharides / Q000633:toxicity; D008297:Male; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis
chemical_list: D004731:Endotoxins; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; C044101:endotoxin, Escherichia coli