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Phagocytosis of Gram‐negative bacteria by a unique CD14‐dependent mechanism
Author(s) -
Schiff Deborah E.,
Kline Lois,
Soldau Katrin,
Lee J. D.,
Pugin Jerome,
Tobias Peter S.,
Ulevitch Richard J.
Publication year - 1997
Publication title -
journal of leukocyte biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.819
H-Index - 191
eISSN - 1938-3673
pISSN - 0741-5400
DOI - 10.1002/jlb.62.6.786
Subject(s) - biology , phagocytosis , gram negative bacteria , mechanism (biology) , microbiology and biotechnology , bacteria , gram , gram positive bacteria , genetics , escherichia coli , gene , philosophy , epistemology
THP‐l‐derived cell lines were stably transfected with constructs encoding glycophosphatidylinositol (GPI) ‐anchored or transmembrane forms of human CD14. CD14 expression was associated with enhanced phagocytosis of serum (heat‐inactivated) ‐opsonized Escherichia coli (opEc). Both the CPI‐anchored and transmembrane forms of CD14 supported phagocytosis of opEc equally well. Lipopolysaccharide‐binding protein (LBP) played a role in CD14‐dependent phagocytosis as evidenced by inhibition of CD14‐dependent phagocytosis of opEc with anti‐LBP monoclonal antibody (mAb) and by enhanced phagocytosis of E. coli opsonized with purified LBP. CD14‐dependent phagocytosis was inhibited by a phosphatidylinositol (PI) 3‐kinase inhibitor (wortmannin) and a protein tyrosine kinase inhibitor (tyrphostin 23) but not a protein kinase C inhibitor (bisindolylmaleimide) or a divalent cation chelator (ethylenediaminetetraacetate). Anti‐LBP mAb 18G4 and anti‐CD 14 mAb 18E12 were used to differentiate between the pathways involved in CD14‐dependent phagocytosis and CD14‐dependent cell activation. F(ab′) 2 fragments of 18G4, a mAb to LBP that does not block cell activation, inhibited ingestion of opEc by THP1‐wtCD14 cells. 18E12 (an anti‐CD14 mAb that does not block LPS binding to CD14 but does inhibit CD14‐dependent cell activation) did not inhibit phagocytosis of LBP‐opEc by THP1‐wtCD14 cells. Furthermore, CD14‐dependent phagocytosis was not inhibited by anti‐CD 18 (CR3 and CR4 β‐chain) or anti‐Fcγ receptor mAb. J. Leukoc. Biol . 62: 786–794; 1997.