To investigate the role of interleukin 1 (IL-1) in
Lyme arthritis we assayed synovial fluids (SF) for the presence of IL-1 activity. Crude SF from patients with
Lyme disease showed IL-1-like activity. Chromatography of joint fluids revealed activity at 15-20,000 daltons. Two populations of cells were grown, which produced significant IL-1 activity when stimulated with the
Lyme disease spirochete or its lipopolysaccharide. IL-1 activity from SF or stimulated cells was neutralized with an antihuman IL-1 antibody. Our results suggest IL-1 is important in the pathogenesis of
Lyme arthritis, and is similar to other arthritides.