Complement components C1q, C1r/C1s, and C1inh in rheumatoid arthritis

Objective. To analyze the synovial site and the cell types expressing C1q, C1r/C1s, and C1–esterase inhibitor (C1INH) and to characterize newly synthesized C1q in patients with rheumatoid arthritis (RA). Methods. Tissue and primary cell cultures of synovium from RA patients were analyzed for C1q, C1r/C1s, and C1INH by Northern blotting, in situ hybridization, and pulse-chase experiments for C1q. Results. The de novo synthesis of C1q, C1r/C1s, and C1INH in synovium and primary cell cultures was proven by Northern blot and by antigenic and functional analysis. In in situ hybridization experiments, the synovial lining cell layer was identified as the site of C1q, C1r, and C1INH expression. In …