Identification of two novel LPS-binding proteins in Kupffer cells: implications in TNF-alpha production.
Using a combination of gel-exclusion chromatography and ligand binding with [(125)I]-lipopolysaccharide (LPS), we discovered two novel endotoxin-binding proteins, p31(LPB) and p34(LPB), in Kupffer cells. Their molecular masses suggest that these are previously undescribed LPS-binding proteins (LBPs). Evidence from detergent-based cell extractions shows that these proteins are probably transmembrane or located on the inner leaflet of the lipid bilayer. We have partially purified the proteins from detergent extracts of Kupffer cells and proven that they bind diphosphoryl lipid A, an interaction associated with TNF-alpha production. The proteins do not bind monophosphoryl lipid A. Diphosphoryl lipid A binding occurs in the absence of serum, suggesting a mechanism of cytokine production distinct from that involving CD14 and lipopolysaccharide-binding protein (LPB). The two proteins were not detectable in resident peritoneal macrophages or in a number of other cell lines of the macrophage/monocyte lineage, suggesting specificity towards terminally differentiated macrophages such as Kupffer cells.
Thomas
Peter
P
Laboratory of Cancer Biology, Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA. peterthomas@creighton.edu
Lazure
Donald A
DA
Moussa
Runna
R
Bajenova
Olga
O
Burke
Peter A
PA
Ganguly
Aniruddha
A
Forse
R Armour
RA
D000209:Acute-Phase Proteins / Q000502:physiology*; D000818:Animals; D002352:Carrier Proteins / Q000502:physiology*; D007728:Kupffer Cells / Q000502:physiology*; D008024:Ligands; D008050:Lipid A / Q000378:metabolism; D008070:Lipopolysaccharides / Q000493:pharmacokinetics; D016676:Macrophages, Alveolar / Q000502:physiology; D017737:Macrophages, Peritoneal / Q000502:physiology; D008297:Male; D008562:Membrane Glycoproteins / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D002352:Carrier Proteins; D008024:Ligands; D008050:Lipid A; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D014409:Tumor Necrosis Factor-alpha; D000099231:Lipopolysaccharide-Binding Protein