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Granulocyte-macrophage colony-stimulating factor down-regulates CD14 expression on monocytes
M Kruger1, J G Van de Winkel, T P De Wit
1Department of Pathophysiology, Catholic University of Leuven, Belgium.
Abstract:
CD14 is a differentiation-stage-linked glycosyl-phophatidyl-inositol-linked glycoprotein on human peripheral blood monocytes and tissue macrophages, which functions as a receptor for lipopolysaccharide. Here, the effects of granulocyte macrophage colony-stimulating factor (GM-CSF1 a cytokine with proliferation- and differentiation-inducing properties on myeloid lineage cells, were studied on CD14 expression by peripheral blood cells. GM-CSF down-regulated the membrane expression of CD14 on monocytes while it up-regulated expression on neutrophils. GM-CSF also decreased the spontaneous release of CD14 in monocyte culture supernatants. Down-regulation of CD14 expression and release was accompanied by a decrease in the mRNA transcript for CD14, suggesting that it most likely reflects an effect on the transcriptional level. The functional significance of this phenomenon, and its potential relation to the terminal differentiation of monocytes, are discussed.
Insights
Granulocyte macrophage colony-stimulating factor (GM-CSF) alters CD14 expression on monocytes and neutrophils. This cytokine impacts CD14 levels at the transcriptional level, affecting monocyte differentiation.
Area of Science:
- Immunology
- Cell Biology
- Hematology
Background:
- CD14 is a key glycoprotein receptor for lipopolysaccharide on monocytes and macrophages.
- Granulocyte macrophage colony-stimulating factor (GM-CSF) influences myeloid cell proliferation and differentiation.
Purpose of the Study:
- To investigate the effects of GM-CSF on CD14 expression in human peripheral blood cells.
- To explore the impact of GM-CSF on CD14 release and its underlying transcriptional regulation.
Main Methods:
- Flow cytometry was used to assess membrane CD14 expression on monocytes and neutrophils.
- Quantitative reverse transcription PCR (RT-PCR) was employed to analyze CD14 mRNA levels.
- Monocyte cultures were established to measure spontaneous CD14 release into supernatants.
Main Results:
- GM-CSF significantly down-regulated membrane CD14 expression on monocytes.
- GM-CSF up-regulated membrane CD14 expression on neutrophils.
- Spontaneous release of soluble CD14 from monocytes decreased following GM-CSF treatment, correlating with reduced CD14 mRNA transcripts.
Conclusions:
- GM-CSF modulates CD14 expression on myeloid cells, primarily at the transcriptional level.
- The observed changes in CD14 expression and release may be linked to GM-CSF-induced monocyte differentiation.
- Further research is warranted to elucidate the functional implications of these findings in immune responses.