Studies on interleukin-1-induced arthritis.

IL-1 induces PMN and monocyte infiltration when injected into rabbit knee joints (1). This transient synovitis is associated with depletion of proteoglycan from the articular cartilage matrix. However, it is not clear whether the cartilage proteoglycan depletion is dependent on the infiltrating leucocytes. Consequently, we have investigated the effect of intra-articular injection of interleukin-1 in rabbits depleted of circulating PMN and monocytes with nitrogen mustard.