Characterization of C1q, C1s and C1 Inh synthesized by stimulated human monocytes in vitro

C1q, C1s and C1 super(-) Inh synthesized and secreted by human monocytes were characterized by SDS-PAGE. C1q is formed of three chains A (M sub(r) similar to 35,000), B (M sub(r) similar to 33,000) and C (M sub(r) similar to 25,000) which are associated in two subunits A-B and C-C. It appears identical to C1q purified from plasma. C1s is secreted as a nonactivated, monocatenar protein of M sub(r) similar to 87,000 identical to proenzymic C1s from plasma. Secreted C1u- Inh (M sub(r) similar to 100,000) has a slightly higher M sub(r) than purified plasmatic C1u- Inh. Monensin treatment of the cells favours the intracytoplasmic accumulation of products at various glycosylation stages.