Binding of a membrane proteoglycan from Klebsiella pneumoniae and its derivatives to human leukocytes.
The binding of a membrane proteoglycan from a non-encapsulated strain of Klebsiella pneumoniae (Kp-MPG) and four derivatives thereof, to human leukocytes, was investigated by indirect immunofluorescence using biotinylated F(ab')2 fragments of anti-Kp-MPG antibodies and the streptavidin-phycoerythrin amplification system in flow cytometry. Four Kp-MPG derivatives were studied: 1/ an acylpoly(1,3)galactoside (APG), 2/ an APG preparation submitted to acid hydrolysis which removed all fatty acids, but left intact the galactose chain of APG (GC-APG), 3/ a preparation obtained by mild alkaline hydrolysis, containing additional ester-linked C14 and C16 fatty acids bound to the APG molecule (EFA-APG) and 4/ a polymer of the latter compound (APG pol). Kp-MPG, APG and EFA-APG were shown to bind exclusively to monocytes at the lowest concentrations (from 0.15 to 3 microM APG). At higher concentrations, these compounds interacted with polymorphonuclear leukocytes, and with lymphocyte subsets in the following decreasing order: B cells, NK cells, CD8+ and CD4+ lymphocytes. Neither APG pol or GC-APG nor K. pneumoniae smooth LPS showed significant binding to leukocytes. However Kp-LPS treated by drastic alkaline hydrolysis displayed binding properties similar to those of APG. Removal of the ester-linked C14 and C16 fatty acids from EFA-APG did not affect the binding of the molecule. The capacity of cells from the myelomonocytic lineage to bind Kp-MPG and APG was very low in phenotypically immature cell lines (HL60 and U937) as compared with monocytes or polymorphonuclear cells. Treatment of U937 cells with interferon-gamma up-regulated their APG binding capacity along with the expression of the integrin CD 11 b and the CD 14 molecule, whereas monocytes exposed to interferon-gamma showed an increased binding of APG associated with an elevated expression of the galactose specific lectin Mac-2. The data demonstrate a preferential binding of Kp-MPG and APG to cells of the monocyte/macrophage lineage. APG binding does not involve the poly (1,3) galactose chain and the ester-linked C14 and C16 fatty acids but requires the presence of the hydrophobic part of the molecule.
Hmama
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INSERM U80 CNRS URA 1177 UCBL, Hôpital E. Herriot, Lyon, France.
Normier
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Kouassi
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Flacher
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Binz
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Revillard
J P
JP
D000918:Antibody Specificity; D002460:Cell Line; D005434:Flow Cytometry; D006358:Hot Temperature; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000472:pathogenicity*; D007962:Leukocytes / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000378:metabolism; D011509:Proteoglycans / Q000378:metabolism*
D007140:Immunoglobulin Fab Fragments; D008070:Lipopolysaccharides; D011509:Proteoglycans