[Metabolism of glycoproteins and fibronectin in skin fibroblasts of patients with rheumatoid arthritis].

The distribution in the cellular monolayer of the de novo synthetized pre-labeled glycoproteins and fibronectin upon culturing of fibroblasts in the medium with low serum content was analyzed. It was found that in rheumatoid arthritis (RA) the amount of total glycoproteins on the surface and within fibroblasts is higher and in the extracellular matrix is lower than in skin fibroblasts of healthy donors (HD). However, the amount of pre-labeled fibronectin on the surface of skin fibroblasts from patients with RA was considerably lower than in those from HD This finding as well as a rapid decrease in the amount of pre-labeled fibronectin in the extracellular matrix of RA fibroblasts is indicative of a more rapid metabolism of this protein in RA. In the skin fibroblasts from HD there was a practically uniform decrease in the amount of pre-labeled fibronectin in the cellular monolayer. The presence of caseinolytic activity in the culture medium even upon the first day of cell culturing in the serum-free medium, as well as the effect of various proteinase inhibitors on glycoprotein content in the cellular monolayer provide evidence that the rate of glycoprotein and fibronectin metabolism, especially in connective tissue cells of patients with RA, might possibly be determined not only by the level of their synthesis but also by the level of proteolytic activity in the connective tissue cells.