LOCALIZATION OF C-REACTIVE PROTEIN IN SYNOVIUM OF PATIENTS WITH RHEUMATOID ARTHRITIS

Abstract

In patients with rheumatoid arthritis (RA), persistent elevation of C-react1ve protein (CRP) is related to the presence of disease activity. Since CRP can activate complement and activated complement may be involved in the pathogenesis of RA, possible synovlal localization of CRP was examined. Sections of synovial tissues from 6 patients with RA, 2 patients with degenerative osteoarthritis and 4 patients with diseases unrelated to RA were studied using fluorescent antisera against CRP, IgG, IgA and fibrinogen. The results were quite clear: CRP localizes in individual nuclei scattered in the outer region of the synovial nesothelium of RA patients. CRP localization was quite unlike that of the other proteins studied and was not found in non-RA synovia. Nuclear bound CRP was not of local origin since tissue cultures of RA synovia did not produce CRP and did produce IgG and IgA. The observed synovial binding of CRP is consistent with the possibility that complement activation by CRP may be involved in the pathogenesis of RA. It is also clear, however, that specific nuclei in RA synovia contain an abnormal substance or agent which can bind CRP. The degree of nuclear binding was found to be independent of serum or joint fluid levels of CRP; thus the anomalous nuclear material is independent of CRP synthesis and could possibly represent the presence of a virus.

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