The demonstration of an interleukin-2 like activity in the synovial fluids of rheumatoid arthritis patients.

It has been shown that synovial tissues and fluids contain activated T lymphocytes. We examined the synovial fluids of rheumatoid arthritis patients and control (noninflammatory) fluids for the presence of interleukin 2 (IL-2) activity, a lymphokine essential to maintaining cells in an activated state. Using an IL-2 dependent T cell line it was found that 10/14 (71%) of rheumatoid synovial fluids contained IL-2 like activity while 0/8 control fluids demonstrated activity. The active material was resistant to heat (56 degrees C for 1h), was less than 50,000 molecular weight by gel filtration fractionation and was not precipitated by 50% saturated ammonium sulphate. It is therefore not immune complex in nature.