In Vitro Synthesis of the First Component of Complement (C1) by Human and Guinea Pig Peritoneal Macrophages

Abstract

Abstract The C1-subcomponent C1q was described to be synthesized by isolated macrophages as shown by detection of radiolabeled C1q precipitin lines developed with an anti-C1q antiserum (Stecher, V. J., and Thorbecke, G. J., J. Immunol. 99, 643 (1967). The proof of the additional synthesis of the two other C1-subcomponents C1r and C1s by macrophages failed so far. Evidence is presented that whole C1 activity (i.e., C1q, C1r, and C1s) was detectable in the supernatants of serum-free short-term cultured human as well as guinea pig peritoneal macrophages. Petri dishes covered with glutaraldehyde cross-linked BSA were used for culturing the monolayers in M199 for 72 to 96 hours at 37°C. The function of C1 was tested hemolyticly by binding to EA or to EAC4 (C1q function) and, after washing the cells, by the following generation of C3 convertase activity from C4 and C2 (C1s function). No C1 activity was found in cultures containing more than 0.1% of heat-inactivated fetal calf or autologous serum.