Isolation and characterization of maerophage-derived C1q and its similarities to serum C1q

Recently, we have shown that the collagen-like, Fc-recognizing subcomponent C1q of the first complement component is synthesized by human, guinea pig and mouse peritoneal macrophages. To test whether macrophages may contribute to the serum pool of C1q, C1q was purified from guinea pig serum and from guinea pig peritoneal macrophage supernatants and compared for similarities. Both molecules had a similar sedimentation rate (macrophage C1q: 11.3 S, serum C1q: 11.2 S) and showed on sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing conditions three identical bands with molecular weights of Mr, 29 000, Mr, 27 000 and Mr 23 000 for the A, B and C chains, respectively. Both …