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Ultrastructural and Immunocytochemical Study of the Uptake and Distribution of Bacterial Lipopolysaccharide in Human Monocytes
Author(s) -
Kang YuanHsu,
Dwivedi R.S.,
Lee CheHung
Publication year - 1990
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.48.4.316
Subject(s) - lipopolysaccharide , biology , intracellular , monocyte , microbiology and biotechnology , horseradish peroxidase , fluorescein isothiocyanate , biochemistry , immunology , physics , quantum mechanics , fluorescence , enzyme
Interaction of bacterial lipopolysaccharide (LPS) with monocytes stimulates production of a variety of mediators that are involved in the pathogenesis of septic shock and wound repair. We report here the mechanisms of LPS uptake and intracellular distribution of LPS in human monocytes. Ficoll‐Hypaque‐purified peripheral mononuclear cells (PBMC) were exposed to LPS from rough Escherichia coli (J5) or to biotin‐conjugated LPS (biotin‐LPS) from smooth E. coli (0111:B4), or to fluorescein isothiocyanate‐conjugated LPS of E . coli (055:B5) at 37° for various times and processed for electron microscopy, immunocytochemistry, and flow cytometry. Monocytes were identified by the presence of numerous cytoplasmic peroxidase‐positive granules or by monoclonal antibodies against monocyte. LPS micelles were identified by their specific bilayer structure, staining of horseradish peroxidase reaction product, or colloidal gold using biotin‐LPS or a monoclonal antibody to LPS. Binding of LPS to cell surface was observed 5 min after incubation with LPS. Intracellular localization of LPS micelles was found 30 min following exposure to LPS. Prolonged incubation with LPS increased intracellular LPS. Intracellulary, LPS micelles were found in large membrane‐bound vacuoles, in small vesicles, and in the cytoplasm and nucleus. They were also observed in association with the cytomembrane of various organelles. The overall results indicate that LPS may be taken up by monocytes by direct passive diffusion through ruptures of plasma membrane, pinocytosis, and phagocytosis, involving specific and/or nonspecific binding, and suggest that peripheral blood monocytes play an important role in clearance of LPS; that LPS may have broad effects on cell functions; and that the nonspecific binding to various cytomembranes may be destructive to cell organelles and cells in general.