Published online Apr 15, 1998. doi: 10.3748/wjg.v4.i2.137
Revised: January 22, 1998
Accepted: March 15, 1998
Published online: April 15, 1998
AIMS: To study the regulatory effects of bacterial lipopolysaccharide (LPS) in murine macrophage proliferation.
METHODS: Using murine peritoneal exudate macrophage (PEM) and macrophage cell line J774A.1 as targets, LPS effects on M-CSF and granulocyte-macrophage colony-stimulating factor (GM-CSF) stimulated macrophage colony-forming cells (CFU-M) were detected. 125I-GM-CSF receptor binding assay was used to examine LPS regulation on GM-CSF receptor expression. RT-PCR was employed to test TGF-β1 inhibition on IFN-γ mRNA expression on macrophage induced by LPS.
RESULTS: Without direct effect on macrophage proliferation, LPS could inhibit the macrophage proliferation stimulated by GM-CSF. However, with the concomitant existence of GM-CSF and TGF-β1, the LPS inhibitory effect was eliminated. RT-PCR analysis indicated that the strongest macrophage growth inhibitory factor IFN-γ mRNA expression in macrophage induced by LPS was remarkably sup-pressed by TGF-β1, 125I-GM-CSF receptor binding assay showed that LPS could enhance GM-CSF receptor expression likewise as TGF-β1.
CONCLUSIONS: LPS is involved in the network of macrophage proliferative regulation by multiple cytokines, displaying inhibitory and stimulatory effects based on the coexisting cytokines.