DISTRIBUTION OF MACROPHAGES IN RHEUMATOID SYNOVIAL-MEMBRANE AND ITS ASSOCIATION WITH BASIC ACTIVITY

Rheumatoid arthritis (RA) is an inflammatory disease of the synovial m embrane, which results in the destruction of joints by inflammatory pa nnus. The synovial membrane shows proliferation and cellular infiltrat es on microscopy with signs of chronic and acute inflammation. Macroph ages are thought to play a central role in the pathogenesis of RA. We examined synovial membrane specimens of 21 RA patients using morpholog ical, immunohistological and enzyme histochemical methods for number a nd distribution of macrophages. We were able to identify 41.5 +/- 8.8% of lining cells as macrophages, depending on the method used. In abun dant diffuse lymphocellular infiltrates, 23.4 +/- 11.1% of mononuclear cells were macrophages. In addition, most cells in the region of tumo rlike proliferation and a stromal population of fibroblastlike cells w ere detected by macrophage markers. Although cell number in synovial m embrane increases drastically, we did not find correlations between th e relative amount of macrophages in these regions and basic activity. Basic activity includes proliferative reaction as well as lymphoplasma cellular and mononuclear infiltration - both signs of an immunopatholo gical process. In contrast, using enzymes or activation markers, there was a clear correlation. We consider that a constant high percentage of macrophages in RA synovial membrane is present regardless of any ac tual inflammatory process.