Distribution of rat C5a anaphylatoxin receptor

The anaphylatoxin, complement 5a (C5a), plays a key role in mediating various inflammatory reactions following complement activation. Several investigators have reported that C5a receptor (C5aR) is expressed in non-myeloid cells under certain conditions or in different cell lines. In our study, the abundance of C5aR-positive myeloid cells in rats depended on the organs examined. C5aR was usually expressed at the site of exposure to pathogens, such as in salivary gland or lung, and was up-regulated in liver in the inflammatory state induced by lipopolysaccharide (LPS) administration. Furthermore, the increased expression of C5aR antigen was not accompanied by an increase in C5aR mRNA in Kupffer cells following LPS challenge.