ONCOPROTEIN EXPRESSION IN HUMAN SYNOVIAL TISSUE - AN IMMUNOHISTOCHEMICAL STUDY OF DIFFERENT TYPES OF ARTHRITIS

Based on the fact that synovial lining cells have some properties of t ransformed-appearing cells, we have examined the expression of Myc, My b, Fos, Jun and Ras oncoproteins in synovial tissues from patients wit h different types of arthritis. Formalin-fixed and paraffin-embedded s ections of synovial tissue from 12 patients with rheumatoid arthritis (RA), 14 with reactive arthritis (ReA), nine with other seronegative a rthritis (OSA), seven with bacterial arthritis (BA), eight with probab le bacterial arthritis (PEA) and eight with osteoarthritis (OA) were s tudied using the immunoperoxidase staining technique. The oncoproteins studied were expressed both in the synovial lining layer and in the s ublining layer, consisting of lymphocytes, other inflammatory cells an d blood vessels. Among the six disease entities, RA and OA appeared to be the most distinct, whereas the results obtained for ReA and OSA, a nd on the other hand for BA and PEA, closely resembled each other. The expression of Myc, Myb, Fos and Jun was significantly correlated both to the degree of synovial hypercellularity and the synovial lymphocyt ic infiltration. For Ras, such a correlation could not be seen. We con clude that we find no evidence of a cell lineage-specific or a disease -specific abnormality of proto-oncogene products in RA, and the expres sion of these oncoproteins is consistent with inflammation rather than with any primary abnormality of cell growth.