Interleukin-6 secretion by bacterial lipopolysaccharide-stimulated bovine alveolar macrophages in vitro.
Interleukin-6 (IL-6) is a pluripotent cytokine that may play a role in pulmonary defense against bacterial pathogens. We have quantitated the response of bovine alveolar macrophages (bAM) to bacterial lipopolysaccharide (LPS; E. coli 055: B5) in vitro using the IL-6 sensitive 7TD1 cell line. Bacteria LPS in the absence of serum induced IL-6 secretion from bAM (1 x 10(6) ml-1) over a range of LPS concentrations from 10 ng ml-1 to 10 micrograms ml-1. This resulted in IL-6 levels ranging from approximately 5 to over 200 U ml-1.IL-6 secretion by from approximately 5 to over 200 U ml-1.IL-6 secretion by LPS-stimulated bAM was increased by 24 h poststimulation, and continued to increase up to 72 h after stimulation. Fetal bovine serum (FBS, 1% vol/vol; 320 micrograms ml-1) enhanced IL-6 secretion from macrophages in the presence of LPS by approximately 10-fold compared with LPS alone. A bovine serum fraction (1 microgram ml-1 protein) prepared using ion-exchange chromatography also markedly enhanced IL-6 secretion versus LPS alone. The stimulatory effect of IL-6-like activity in the bAM supernatants was neutralized by an anti-human IL-6 polyclonal antibody. Northern blot analysis revealed increased IL-6 mRNA at 2 h poststimulation with LPS + FBS, peak levels at 4 h, and levels were decreased by 6 h poststimulation. Results suggest that IL-6 is secreted by bovine alveolar macrophages, and that bacterial LPS and serum components synergize to produce this response.
Jian
Z J
ZJ
Department of Pathology, College of Veterinary Medicine, University of Tennessee, Knoxville 37901, USA.
Yang
Z
Z
Miller
M S
MS
Carter
C D
CD
Slauson
D O
DO
Bochsler
P N
PN
D000818:Animals; D019138:Antibodies, Blocking; D002417:Cattle / Q000097:blood / Q000276:immunology*; D002460:Cell Line; D006801:Humans; D066298:In Vitro Techniques; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation / Q000235:genetics / Q000276:immunology; D016676:Macrophages, Alveolar / Q000276:immunology*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000093242:Interleukin-6 Inhibitors
D019138:Antibodies, Blocking; D015850:Interleukin-6; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D000093242:Interleukin-6 Inhibitors