This invention is directed to a soluble recombinant fused protein which is stable in the mammalian circulatory system comprising a polypeptide which contains a recognition site for a target molecule, such as a complement receptor site, and is joined to the N-terminal end of an immunoglobulin chain. The invention is also directed to a construct comprising a plurality of peptides containing short consensus repeats having a complement binding site attached to a soluble, physiologically compatible, macromolecular carrier. The invention is particularly useful for inhibiting complement activation or complement-dependent cellular activation in mammals.