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Human monocyte CD14 Is upregulated by lipopolysaccharide

Item Type:Article
Title:Human monocyte CD14 Is upregulated by lipopolysaccharide
Creators Name:Landmann, R. and Knopf, H.P. and Link, S. and Sansano, S. and Schumann, R. and Zimmerli, W.
Abstract:Membrane CD14 is involved in lipopolysaccharide (LPS)-induced monocyte activation; it binds LPS, and antibodies against CD14 block the effects of low-dose LPS. It is unknown how LPS regulates its own receptor CD14 in vitro. Therefore, we investigated the effects of LPS on CD14 mRNA and membrane and soluble CD14 (mCD14 and sCD14, respectively) in human monocytes and macrophages. No changes were observed during the first 3 h of LPS stimulation. After 6 to 15 h, LPS weakly reduced CD14 mRNA and mCD14 and transiently enhanced sCD14 release. A 2-day incubation with LPS caused increases in the levels of CD14 mRNA (2-fold), mCD14 (2-fold), sCD14 (1.5-fold), and LPS-fluorescein isothiocyanate binding (1.5-fold); a 5-h incubation with LPS was sufficient to induce the late effects on mCD14 and sCD14. The maximal effect on mCD14 and sCD14 was reached with > or = 1 ng of LPS per ml; the proportional distribution of the two sCD14 isoforms was not modified by LPS. Besides rough and smooth LPS, lipid A, heat-killed Escherichia coli, lipoteichoic acid, and Staphylococcus aureus cell wall extract (10 micrograms/ml) caused similar increases of mCD14. The LPS effect was blocked by polymyxin B but not by anti-tumor necrosis factor alpha, anti-interleukin-6, anti-gamma interferon, and anti-LPS-binding protein. LPS-induced tumor necrosis factor alpha production was abolished after a second 4-h challenge. In contrast, the LPS-induced increases CD14 mRNA, mCD14, and sCD14 were stronger and appeared earlier after a second LPS challenge. In conclusion, CD14 is transcriptionally upregulated by LPS and other bacterial cell wall constituents.
Keywords:CD14 Antigens, Cell Membrane, Drug Dose-Response Relationship, Kinetics, Lipopolysaccharides, Messenger RNA, Monocytes, Physiological Adaptation, Solubility, Tumor Necrosis Factor-alpha, Up-Regulation
Source:Infection and Immunity
Publisher:American Society for Microbiology
Page Range:1762-1769
Date:1 May 1996
Official Publication:http://iai.asm.org/cgi/content/abstract/64/5/1762
PubMed:View item in PubMed

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