Binding of a bacterial acylpoly(1,3)galactoside to human blood leucocytes.
The binding of a 34-kDa (mol. wt.) acylpoly(1,3)galactoside (APG) extracted from a membrane proteoglycan of Klebsiella pneumoniae to human blood leucocytes was investigated. APG is made of a long poly(1,3)galactose chain, a core-like region and a lipid moiety which comprises two glucosamine residues bound to a phosphate group and two beta OH myristic acids. Fluoresceinated APG was shown to bind preferentially to monocytes and to a lesser extent to polymorphonuclear neutrophils, as determined by flow cytometry. Binding of fluoresceinated APG was inhibited by unlabelled APG; it was concentration dependent, but not saturable, with rapid kinetics. It occurred at +4 degrees C but was markedly increased at 37 degrees C. It involved trypsin-sensitive molecules on the membrane of monocytes. Neither the parent proteoglycan nor lipopolysaccharide from K. pneumoniae or Salmonella minnesota competed for APG binding. A minor non-specific binding to lymphocytes, occurring predominantly on B cells, was observed. Unlike that of lipopolysaccharide, the APG binding was not blocked by polymyxin B sulphate. Interaction between the galactose chain of APG and the galactose receptor does not account for the binding of APG to monocytes because the galactose receptor (Mac-2) is expressed at high density on activated macrophages but not on monocytes. Despite its strong binding to human blood monocytes, APG displayed a much weaker activity than K. pneumoniae membrane proteoglycan with respect to induction of monocyte cytokine synthesis. When administered as a Technetium 99 conjugate, APG was shown to label inflammatory foci in experimental animals, and its property as a marker of macrophages is currently being evaluated in clinical trials.
Hmama
Z
Z
Laboratory of Immunology, INSERM U80 CNRS URA 1177 UCBL, Hôpital E. Herriot, Lyon, France.
Kouassi
E
E
Panaye
G
G
Delassan
S
S
Normier
G
G
Binz
H
H
Revillard
J P
JP
D001667:Binding, Competitive; D005697:Galactosides / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000276:immunology; D008214:Lymphocytes / Q000378:metabolism; D009000:Monocytes / Q000378:metabolism*; D009439:Neuraminidase / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D010084:Oxidation-Reduction; D011112:Polymyxin B / Q000494:pharmacology; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D011509:Proteoglycans / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D016897:Respiratory Burst; D013329:Structure-Activity Relationship; D013696:Temperature; D014357:Trypsin / Q000494:pharmacology
D005697:Galactosides; D011135:Polysaccharides, Bacterial; D011509:Proteoglycans; D009439:Neuraminidase; D014357:Trypsin; D011112:Polymyxin B