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In situ expression of protooncogenes and Fas/Fas ligand in rheumatoid arthritis synovium.

OBJECTIVE
To examine the relationship among the expression of protooncogenes such as c-fos and c-myc, Fas antigen, Fas ligand, and apoptosis in the synovial tissue of patients with rheumatoid arthritis (RA).


METHODS
The expression of c-fos, c-myc, Fas antigen, and Fas ligand was examined in synovial tissues of 6 patients with RA and 4 with osteoarthritis (OA) using in situ reverse transcriptase (RT) assay and immunohistochemical staining. Apoptosis was detected by TUNEL method in situ.


RESULTS
Expression of protooncogenes, c-fos, and c-myc was detected in all samples from patients with RA, but in only a few cells of OA synovium. 30 to 90% of cells in RA synovium positive for these protooncogenes also coexpressed Fas antigen. Fas positive cells in RA synovium underwent apoptosis to a significant degree. Fas ligand mRNA was detected only in mononuclear cells in RA synovium.


CONCLUSION
The expression of protooncogenes is closely related to Fas mediated apoptosis in RA synoviocytes.