The monoclonal antibody 10/92 recognizes the mouse receptor C5a (C5aR, CD88). The mouse anaphylatoxin C5a is a 74-residu glycopolypeptide which is generated by proteolytic cleavage of the complement factor C5 in the course of complement activation. A variety of biological effects evoked by C5a could be demonstrated, rendering this molecule an important mediator of inflammation, with granulocytes and macrophages as the main target cells. All cellular responses to C5a are specifically mediated by interactions with the membrane bound C5a receptor, a seven transmembrane GTP-binding-protein-coupled receptor that belongs to the rhodopsin supergene family. The 45 kDa C5a receptor is expressed by neutrophils, monocytes/macrophages, dendritic cells, astrocytes and microglia. In contrast, C5a receptor is not detectable on resting or stimulated murine T and B lymphocytes.The monoclonal antibody 10/92 does not inhibit the binding of C5a to its receptor.