Expression of the complement C5a anaphylatoxin receptor (C5aR) on non-myeloid cells

The expression of the complement C5a anaphylatoxin receptor (C5aR) has traditionally been thought to be limited to myeloid blood cells, including neutrophils, monocytes, macrophages, and eosinophils. Immunohistochemistry and ligand-binding studies reported here demonstrate, however, that C5aR is expressed by parenchymal cells of several solid organs, including human liver hepatocytes, lung bronchial and alveolar epithelial cells, and lung vascular smooth muscle and endothelial cells. In addition to C5aR expression in liver and lung, C5aR-specific message is found in other tissues, including the spleen, heart, kidney, and intestine. Collectively, these data indicate that the C5aR is expressed in several different types of cells in liver and lung and in yet undetermined cell types in spleen, heart, intestine, and kidney. Moreover, these data suggest that the C5aR mediates previously unrecognized functions by binding to tissue cells that express the C5aR.