Interleukin-6 in synovial fluid is closely associated with chronic synovitis in rheumatoid arthritis.
Interleukin-6 (IL-6) was detected at low levels in plasma [0.014 +/- 0.006 ng/ml (mean +/- SEM] and in high amounts in synovial fluid [SF; 2.6 +/- 2.2 ng/ml (mean +/- SEM)] of patients with rheumatoid arthritis. No correlation of IL-6 levels in plasma or SF with the ESR (n = 15) or with histological parameters of acute local synovitis (n = 10) was observed. In contrast, SF IL-6 was positively correlated with histological characteristics of chronic synovitis (n = 10; P < or = 0.01) and elevated plasma IgG concentrations (n = 15; P < or = 0.05). In vitro concentrations of IL-6 comparable to those detected in SF increased the production of both IgG and IgM by synovial membrane mononuclear cells. The present results contribute to the view that high local IL-6 concentrations in SF promote chronic synovitis in RA.
Sack
U
U
Department of Medicine III, University of Erlangen-Nuremberg, Germany.
Kinne
R W
RW
Marx
T
T
Heppt
P
P
Bender
S
S
Emmrich
F
F
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood / Q000150:complications* / Q000378:metabolism*; D002908:Chronic Disease; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D007075:Immunoglobulin M / Q000032:analysis; D015850:Interleukin-6 / Q000032:analysis* / Q000378:metabolism / Q000502:physiology; D008297:Male; D008875:Middle Aged; D013582:Synovial Fluid / Q000737:chemistry*; D013583:Synovial Membrane / Q000737:chemistry / Q000473:pathology; D013585:Synovitis / Q000097:blood / Q000150:complications* / Q000378:metabolism*
D007074:Immunoglobulin G; D007075:Immunoglobulin M; D015850:Interleukin-6