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  • 1
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract Pentaacyl diphosphoryllipid A derived from the nontoxic lipopolysaccharide (LPS) of Rhodobacter sphaeroides ATCC 17023 (RsDPLA) did not induce tumour necrosis factor-α nor interleukin-6 release in the murine macrophage-like cell line J774.1. However, it effectively inhibited the induction of these two cytokines by LPS of Salmonella minnesota Re mutant R595 (ReLPA) in a concentration-dependent manner. Maximal inhibition and half-maximal inhibition occured when the ReLPS to RsDPLA mass ratio was 1:30 and 1:1, respectively. A binding study was performed in the presence of serum to determine whether RsDPLA is competing with ReLPS for LPS binding sites on J774.1 cells. This assay allows the determination of LPS binding to J774.1 cells via a mechanism involving CD14, a receptor for complexes of LPS with LPS binding protein (LBP), and its possible inhibition. The results show that RsDPLA strongly inhibits the binding of 125I-labelled ReLPS to J774.1 cells. Maximal and one-half maximal inhibition of binding occured when the ReLPS to RsDPLA mass ratios were 1:2.5 and 1:0.5, respectively. It was found that the inhibition of binding by RsDPLA was much stronger than that by unlabelled ReLPS. These results suggest that RsDPLA is competing with ReLPS for CD14-dependent recognition of LPS on J774.1 cells.
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  • 2
    ISSN: 1574-695X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Abstract Natural partial structures of lipopolysaccharide (LPS) as well as synthetic analogues and derivatives of lipid A were compared with respect to inhibit the binding of 125I-labelled Re-chemotype LPS to mouse macrophage-like J774.1 cells to induce cytokine-release in J774.1 cells. LPS, synthetic Escherichia coli-type lipid A (compound 506) and tetraacyl percursor Ia (compound 406) inhibited the binding of 125I-LPS to macrophage-like J774.1 cells and induced the release of tumor ncerosis factor α (TNFα) and interleukin 6 (IL-6). Deacylated R-chemotype LPS preparations were completely inactive in inhibiting binding and in inducing cytokine-release. Among tetraacyl compounds, the inhibition-capacity of LPS-binding was in decreasing order: PE-4 (α-phosphonooxyethyl analogue of 406)〉406⪢〉404(4′-monophosphoryl partial structure of 406)〉405 (1-monophosphoryl partial structure of 406). In the case of hexaccyl preparations, compounds 506, PE-1 (α-phosphonooxyethyl analogue of 506) and PE-2 (differing from PE-1 in having 14:0 at positions 2 and 3 of the reducing GlcN) inhibited LPS-binding and induced cytokine release equally well, whereas preparation PE-3 (differing from PE-2 in containing a β-phosphhonooxyethyl group) showed a substantially lower capacity in binding-inhibition and cytokine-induction. The conclusion is that chemical changes in the hydrophilic lipid A backbone reduce the capacity of lipid A to bind to cells, whereas the number of fatty acids determines the capacity of lipid A to activate cells. These results indicate that the bisphosphorylated hexosamine backbone of lipid A is essential for specific binding of LPS to macrophages and that the acylation pattern plays a critical role for LPS-promoted cell activation, i.e. cytokine induction.
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  • 3
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Lipopolysaccharide-(LPS) binding proteins present on murine-lymphocyte and macrophage-like cell lines were identified by a ligand-blotting method and subsequent immunological detection of bound LPS. Membrane proteins of the murine-pre-B-cell line 70Z/3 were separated by SDS-PAGE, transferred electrophoretically onto nitrocellulose, and the blot was incubated with LPS of the Salmonella minnesota Re-mutant R595 (mRe-LPS). LPS bound to proteins on nitrocellulose was immunologically detected by anti-mRe-LPS antibodies; LPS was associated with one of the membrane proteins of 70Z/3 cells. This protein was 40 kDa under reducing and 45 kDa under non-reducing conditions, respectively. Treatment of 70Z/3 cells with pronase led to the disappearance of the LPS-binding protein indicating its surface location. Excess free lipid A, which represents the biologically active region of LPS, inhibited the binding of mRe-LPS to the protein. This LPS-binding protein was also identified on the pre-B-cell line CYG8, the B-cell line CYG101 and the murine-T-cell line BW5147. It was, however, not detectable on the B-cell line CYG34 and the myeloma-cell line P3-X63-Ag8.653. No other LPS-binding protein could be detected on these cell lines. In the murine-macrophage-like cell line J774.1, two LPS-binding proteins, one of 40 kDa and one of 80 kDa, were detected. These results indicate that mRe-LPS is specifically bound to a 40-kDa protein of lymphocytes, whereas in the case of macrophages it is associated with two LPS-binding proteins of 40 and 80 kDa.
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