Expression of Glutamine Synthetase in Macrophages

We studied the expression of glutamine synthetase in liver macrophages (Kupffer cells, KCs) in situ and in culture. Glutamine synthetase was detectable at the mRNA and protein level in freshly isolated and short-term-cultured rat liver macrophages. Enzyme activity and protein content were about 9% o...

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Published inThe journal of histochemistry and cytochemistry Vol. 48; no. 3; pp. 415 - 421
Main Authors Bode, Johannes Georg, Peters-Regehr, Thorsten, Kubitz, Ralf, Haussinger, Dieter
Format Journal Article
LanguageEnglish
Published Los Angeles, CA Histochemical Soc 01.03.2000
SAGE Publications
Subjects
Animals
Cell Line
Endothelium - cytology
Endothelium - enzymology
Glutamate-Ammonia Ligase - metabolism
Humans
Immunohistochemistry
Liver - cytology
Liver - enzymology
Macrophages - enzymology
Male
Mice
Microscopy, Confocal
Monocytes - enzymology
Pancreas - cytology
Pancreas - enzymology
Rats
Rats, Wistar
glutamine metabolism
sinusoidal endothelial cells
monocytes
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Summary:We studied the expression of glutamine synthetase in liver macrophages (Kupffer cells, KCs) in situ and in culture. Glutamine synthetase was detectable at the mRNA and protein level in freshly isolated and short-term-cultured rat liver macrophages. Enzyme activity and protein content were about 9% of that in liver parenchymal cells. In contrast, glutamine synthetase mRNA levels in liver macrophages apparently exceeded those in parenchymal liver cells (PCs). By use of confocal laser scanning microscopy and specific macrophage markers, immunoreactive glutamine synthetase was localized to macrophages in normal rat liver and normal human liver in situ. All liver macrophages stained positive for glutamine synthetase. In addition, macrophages in rat pancreas contained immunoreactive glutamine synthetase, whereas glutamine synthetase was not detectable at the mRNA and protein level in blood monocytes and RAW 264.7 mouse macrophages. No significant amounts of glutamine synthetase were found in isolated rat liver sinusoidal endothelial cells (SECs). The data suggest a constitutive expression of glutamine synthetase not only, as previously believed, in perivenous liver parenchymal cells but also in resident liver macrophages.
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ISSN:0022-1554
1551-5044
DOI:10.1177/002215540004800311