The role of serine proteinase in cartilage damage.

Arthritic cartilage from experimental animals has been shown to have a decreased proteoglycan content, a decreased rate of proteoglycan synthesis, and a marked increase in an active serine proteinase when compared with normal articular cartilage. The serine proteinase is transferred from PMN cells into cartilage during the inflammatory response where it increased the rate of proteoglycan degradation and is eventually removed by interaction with the chondrocyte surface. The interaction also results in an inhibition of proteoglycan synthesis by the chondrocytes. Both these factors contribute to the loss of proteoglycan from arthritic cartilage.