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Binding of a Bacterial Acylpoly(1,3)Galactoside to Human Blood Leucocytes
Author(s) -
HMAMA Z.,
KOUASSI E.,
PANAYE G.,
DELASSAN S.,
NORMlER G.,
BlNZ H.,
REVILLARD J.P.
Publication year - 1992
Publication title -
scandinavian journal of immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.934
H-Index - 88
eISSN - 1365-3083
pISSN - 0300-9475
DOI - 10.1111/j.1365-3083.1992.tb02935.x
Subject(s) - lipopolysaccharide , biochemistry , muramyl dipeptide , chemistry , galactose , lipid a , biology , microbiology and biotechnology , immunology , in vitro
The binding of a 34‐kDa (mol. wt.) acylpoly(1,3)galactoside (APG) extracted from a membrane proteoglycan of Klebsiella pneumoinae to human blood leucocytes was investigated. APG is made of a long polyl (1,3)galactose chain, a core‐like region and a lipid moiety which comprises two glucosamine residues bound to a phosphate group and two β 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°C but was markedly increased at 37°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.