COMPLEMENT COMPONENTS C1Q, C1R C1S, AND C1INH IN RHEUMATOID-ARTHRITIS- CORRELATION OF IN-SITU HYBRIDIZATION AND NORTHERN BLOT RESULTS WITHFUNCTION AND PROTEIN CONCENTRATION IN SYNOVIUM AND PRIMARY CELL CULTURES/

Objective, To analyze the synovial site and the cell types expressing Clq, C1q/C1s, and C1-esterase inhibitor (C1INH) and to characterize ne wly synthesized Clq in patients with rheumatoid arthritis (RA), Method s, Tissue and primary cell cultures of synovium from RA patients were analyzed for Clq, C1r/C1s, and C1INH by Northern blotting, in situ hyb ridization, and pulse-chase experiments for Clq, Results, The de novo synthesis of Clq, C1r/C1s, and C1INH in synovium and primary cell cult ures was proven by Northern blot and by antigenic and functional analy sis, In in situ hybridization experiments, the synovial lining cell la yer was identified as the site of Clq, Clr, and C1INH expression, In c ontrast, immunohistologic analysis showed that Clq, Cls, and C1INH pro teins were present in a thin film covering the synovial lining cells, In situ hybridization performed on primary cell cultures provided evid ence that only macrophages were able to express Clq, whereas fibroblas ts and stellate cells synthesized Clr, Conclusion, The synovium is imp ortant for the synthesis and secretion of Clq and C1r/C1s, as well as the control protein C1INH, which supports the idea of a locally occurr ing inflammatory process in RA patients.