Interleukin-6 in synovial fluid and serum of patients with rheumatoid arthritis and other inflammatory arthritides

Arthritis Rheum. 1988 Jun;31(6):784-8. doi: 10.1002/art.1780310614.


Interleukin-6 (IL-6), also called 26-kd protein, hybridoma plasmacytoma growth factor, beta 2-interferon, or B cell stimulatory factor 2, is a recently described human cytokine with multiple growth and differentiation activities. Using a very sensitive bioassay based on the growth factor activity of this protein for B cell hybridomas, we found that IL-6 activity was significantly elevated in synovial fluid from patients with rheumatoid arthritis (RA) or other inflammatory arthritides, as compared with that in a group of patients with osteoarthritis. Moreover, IL-6 was detected in about one-third of the serum samples from patients with RA. In the latter group, we found a significant correlation between serum IL-6 activity and serum levels of C-reactive protein, alpha 1-acid glycoprotein, alpha 1-antitrypsin, fibrinogen, and haptoglobin, which indicates that IL-6 is related to disease activity in patients with RA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arthritis / blood
  • Arthritis / metabolism*
  • Arthritis, Rheumatoid / blood
  • Arthritis, Rheumatoid / metabolism*
  • Growth Substances / metabolism
  • Humans
  • Hybridomas / metabolism
  • Interleukin-6
  • Interleukins / blood
  • Interleukins / metabolism*
  • Synovial Fluid / metabolism*


  • Growth Substances
  • Interleukin-6
  • Interleukins