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Differential expression of the urokinase receptor (CD87) in arthritic and normal synovial tissues
Z Szekanecz1, G K Haines, A E Koch
1Department of Medicine, Northwestern University Medical School, Chicago, Illinois, USA.
Aim:
To determine whether the urokinase plasminogen activator receptor (u-PAR; CD87) exhibits a possible pathogenic role in rheumatoid and osteoarthritis.
Methods:
A semiquantitative, indirect immunoperoxidase histochemical analysis was performed on frozen synovial tissue sections. The recently characterised monoclonal antibody 10G7 recognising transfectants bearing u-PAR was used. Synovial tissue was obtained from 10 patients with rheumatoid arthritis, 10 patients with osteoarthritis, and four normal subjects.
Results:
u-PAR was expressed on 70-90% of synovial tissue lining cells and subsynovial, interstitial macrophages from the arthritis patients, but only on a few myeloid cells from the normal subjects. It was also present on more endothelial cells from the rheumatoid and osteoarthritis patients, than from normal synovial tissue.
Conclusions:
Plasminogen activators are important in joint destruction underlying arthritis. The up-regulated expression of u-PAR in diseased versus normal synovial tissue suggests a role for this antigen in the inflammatory and angiogenic mechanisms underlying rheumatoid and osteoarthritis.