Increased proteolytic activity on the surface of monocytes from patients with rheumatoid arthritis

Abstract

Studies on the expression and localization of the urokinase receptor on peripheral blood monocytes of patients with rheumatoid arthritis (RA), patients with osteoarthritis, and healthy volunteers showed a significant increase in the total number of urokinase receptors on monocytes of patients with RA, compared with osteoarthritis patients or with healthy subjects. The increase in the total number of urokinase receptors in RA was due to an elevation in the number of endogenously occupied urokinase receptors. These data provide evidence that increased proteolytic activity might contribute to the pronounced degradation of cartilage and connective tissue in patients with RA.