Correlation between rheumatoid factor and IL-6 activity in synovial fluids from patients with rheumatoid arthritis.
Synovial fluids (SF) and sera (S) from patients with rheumatoid arthritis (RA) were examined for IgM, IgM-rheumatoid factor (IgM-RF), albumin and interleukin-6 (IL-6) activity. The quotient of SF/S IgM-RF was elevated compared with that of SF/S albumin in 7 patients with seropositive RA, although the quotient of SF/S IgM was lower than that of SF/S albumin. SF IL-6 activity was much higher than serum IL-6 activity in all the 7 RA patients. In synovial fluids from 22 seropositive RA patients, SF IL-6 activity was significantly correlated with the SF IgM-RF, IgG-RF and IgA- less than RF, but not with SF IgM, IgG or IgA. Moreover, SF IgM-RF as well as SF IL-6 activity was significantly correlated with the Westergren erythrocyte sedimentation rate (ESR) or the Lansbury articular index. These results indicate that IL-6 and RF might be produced within the rheumatoid joints as a result of abnormal immune system activation, which is associated with the disease activity of RA. Three of the 4 seronegative RA patients, however, showed high SF IL-6 without detectable levels of SF IgM-RF, indicating that IL-6 alone is not sufficient for IgM-RF production.
Department of Medicine and Physical Therapy, University of Tokyo School of Medicine, Japan.
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Sawada
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Hirohata
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Inoue
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Ito
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001172:Arthritis, Rheumatoid / Q000209:etiology / Q000378:metabolism*; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D015850:Interleukin-6 / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D008297:Male; D008875:Middle Aged; D012217:Rheumatoid Factor / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D013582:Synovial Fluid / Q000737:chemistry* / Q000378:metabolism
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015850:Interleukin-6; D012217:Rheumatoid Factor