RHEUMATOID-FACTOR PRODUCTION BY MONONUCLEAR-CELLS DERIVED FROM DIFFERENT SITES OF PATIENTS WITH RHEUMATOID-ARTHRITIS

To investigate the origin of circulating rheumatoid factor (RF) and th e relation between RF production at different sites in patients with r heumatoid arthritis (RA), mononuclear cells derived from bone marrow, synovium and peripheral blood of patients with RA were examined for th e presence of plasma cells and for their capacity to produce RF and ot her immunoglobulins in vitro. Analysis of culture supernatants for the presence of immunoglobulins demonstrated that cells derived from bone marrow, synovium and peripheral blood were all found to be capable of producing every immunoglobulin and RF isotype investigated. No signif icant correlations were found between concentrations of immunoglobulin isotypes produced by cells derived from different sites of one indivi dual. Significant correlations were found, however, between concentrat ions of RF isotypes produced by cells derived from the three sites. Th ese results indicate that the production of RF in the different compar tments is not an autonomously regulated process. Mononuclear cells der ived from bone marrow were found to be able to produce RF in similar q uantities to cells dissociated from synovial tissue. In combination wi th the fact that circulating immunoglobulins are produced mainly in th e bone marrow, this observation suggests that bone marrow is also a ma jor source of circulating RF.