Effects of isolated rheumatoid synovial cells on cartilage degradation in vitro.

Rheumatoid synovium in coculture with cartilage has been shown to release a factor(s) that stimulates the depletion of glycosaminoglycans (GAG) from cartilage matrix. Human rheumatoid synovium was enzymatically disaggregated and the isolated cells were subjected to a variety of mechanical and immunological treatments. Synovial cell conditioned media (SCCM) were prepared and analyzed for their ability to stimulate GAG depletion. SCCM prepared from increasing concentrations of isolated synovial cells demonstrated cartilage degradative activity in a dose-dependent manner. This activity was characterized as interleukin-1 like and was found mostly within the adherent cell population where the synovial macrophages retained significant degradative ability. T cells alone were found to have no direct degradative effect on cartilage, but their presence appeared to augment the response of the adherent cells. The techniques described here provide a quantitative model for examining the degradative factors from synovium as well as the cellular interactions that promote their release.