The C5a receptor is expressed in normal renal proximal tubular but not in normal pulmonary or hepatic epithelial cells
Article first published online: 25 DEC 2001
Volume 99, Issue 1, pages 38–45, January 2000
How to Cite
Fayyazi, A., Scheel, O., Werfel, T., Schweyer, S., Oppermann, M., Götze, O., Radzun, H. J. and Zwirner, J. (2000), The C5a receptor is expressed in normal renal proximal tubular but not in normal pulmonary or hepatic epithelial cells. Immunology, 99: 38–45. doi: 10.1046/j.1365-2567.2000.00911.x
- Issue published online: 25 DEC 2001
- Article first published online: 25 DEC 2001
- Received 15 March 1999; revised 21 July 1999; accepted 21 July 1999.
C5a, a 74 amino acid peptide cleaved from the complement protein C5, is an extremely potent anaphylatoxin. Expression of the receptor for the anaphylatoxin C5a (C5aR) has been thought to be restricted to cells of myeloid origin. However, recent evidence suggests that the C5aR is also expressed in hepatocytes as well as in pulmonary epithelial, endothelial and smooth muscle cells. In the present study, we investigated the tissue distribution of C5aR by immunohistochemistry in normal human lung, liver, intestine and kidney using well-defined monoclonal antibodies (mAbs) directed against the extracellular N-terminus of the receptor. In all tissues examined, macrophages displayed an abundant expression of C5aR protein. However, in the normal human lung, C5aR expression was not detectable in bronchial and alveolar epithelial cells or in vascular smooth muscle or endothelial cells. In the normal human liver, no C5aR protein was detected in hepatocytes, whereas Kupffer cells strongly expressed the C5aR. In normal human kidney, the C5aR was detectable only in proximal tubular cells. C5aR gene transcription in Kupffer cells and proximal tubular cells was confirmed by in situ hybridization. Thus, our results point to an as yet unknown role of the C5aR in normal renal physiology. In the normal lung and liver, however, previous evidence for the ubiquitous expression of C5aR in epithelial, endothelial and smooth muscle cells in situ should be re-evaluated.