RHEUMATOID-FACTOR PRODUCTION IN THE JOINT

Mononuclear cells derived from bone marrow, synovium and peripheral bl ood of patients with rheumatoid arthritis (RA) were examined for their capacity to produce rheumatoid factor (RF) in order to investigate th e origin of circulating RF. The results demonstrate that mononuclear c ells derived from bone marrow are able to produce IgG-, IgA- and IgM-R F and that the amounts of RF produced by bone marrow cells are not sig nificantly different from that by dissociated synovial cells. Since ci rculating immunoglobulins are mainly derived from the bone marrow this observation suggests that also RF circulating in RA patients mainly o riginates from the bone marrow.