Influence of interleukin-1 on the morphology and proteoglycan metabolism of cultured bovine articular chondrocytes.

Bovine articular chondrocytes cultured in agarose gel in the presence of serum elaborated a highly organized extracellular matrix rich in proteoglycans and collagens. The cultures were evaluated quantitatively by radiosulfate labeling of proteoglycans, and by densitometry following staining with alcian blue. In addition, immunohistochemical methods were used to demonstrate the presence of several components of cartilage proteoglycan molecules. Treatment with Interleukin-1 (Il-1) or retinol resulted in diminished synthesis and enhanced catabolism of matrix proteoglycans, but the chondrocytes were more sensitive to human recombinant Il-1 alpha than to Il-1 beta. Treatment with Il-1 alpha or retinol resulted in a profound disorganization of the residual matrix around the majority of the chondrocytes, while Il-1 beta caused much less severe changes. Some variation in cellular response to Il-1 alpha may result from the heterogeneity previously reported among articular chondrocytes.