Serum components enhance bacterial lipopolysaccharide-induced tissue factor expression and tumor necrosis factor-alpha secretion by bovine alveolar macrophages in vitro.
We have compared the effect of bacterial lipopolysaccharide (LPS) in combination with normal adult bovine serum (NBS), fetal bovine serum (FBS), or a bovine serum fraction on tissue factor expression and tumor necrosis factor alpha (TNF-alpha) secretion by bovine alveolar macrophages. At a concentration of 1 ng/ml, bacterial LPS alone failed to induce measurable tissue factor expression by the macrophages, but the presence of FBS, NBS, or a fraction of normal pooled bovine serum isolated by ion-exchange chromatography (fraction 2) markedly potentiated the effect of LPS. A protein concentration of 64 micrograms/ml NBS, 192 micrograms/ml FBS, and only 640 ng/ml fraction 2 was required to induce maximal tissue factor expression on the macrophages in combination with 1 ng/ml LPS. Comparison of quantities of added serum protein required to induce maximal potentiating effects indicated that fraction 2 was 100 times more potent than whole NBS and 300 times more potent than whole FBS. We similarly found that TNF-alpha secretion by macrophages exposed to LPS was responsive to serum and was highly responsive to fraction 2. LPS alone (1 ng/ml) induced a relatively low level of TNF-alpha secretion by the macrophages, and the presence of FBS, NBS, or fraction 2 potentiated the effect of LPS. A concentration of 64.0 micrograms/ml NBS, 320.0 micrograms/ml FBS, and 3.2 micrograms/ml fraction 2 serum protein induced near-maximal TNF-alpha secretion by the macrophages. Comparison of the concentration of serum protein required to induce these potentiating effects indicated that fraction 2 was approximately 20 times more potent than whole NBS and 100 times more potent than whole FBS. The stimulatory effect of LPS plus fraction 2 serum proteins was dependent on the CD14 receptor, as monoclonal antibodies directed against CD14 (My4, 60bd; 10 micrograms/ml) inhibited tissue factor expression and TNF-alpha secretion by the macrophages.
Yang
Z
Z
Department of Pathobiology, University of Tennessee, Knoxville 37901-1071.
Khemlani
L S
LS
Dean
D F
DF
Carter
C D
CD
Slauson
D O
DO
Bochsler
P N
PN
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015703:Antigens, CD / Q000502:physiology; D015214:Antigens, Differentiation, Myelomonocytic / Q000502:physiology; D001790:Blood Physiological Phenomena; D002417:Cattle; D066298:In Vitro Techniques; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016676:Macrophages, Alveolar / Q000378:metabolism*; D013925:Thromboplastin / Q000096:biosynthesis*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D013925:Thromboplastin