[Proliferation of T-cells, macrophages, neutrophilic granulocytes and fibroblast-like cells in the synovial membrane of patients with rheumatoid arthritis].

The aim of this study was to determine the proliferation rates within the lining layer of the rheumatoid arthritis (RA) synovial membrane (SM) as opposed to the SM of other degenerative and neoplastic joint diseases and to characterize the proliferating cells. 13 RA, 23 osteoarthritis (OA), 21 joint trauma (JT), and 9 synovial sarcoma (SS) specimens were immunostained for Ki-67 and PCNA, silver-stained for nucleolar organizer regions (AgNORs), and double stained with either T-cell- (CD3), macrophage- (CD68), or polymorphonuclear neutrophilic leucocytes (PMN)-markers (CD15). The frequency of PCNA positive synovial lining cells (SLCs) varied from 15.7 +/- 8.7% in RA (mean +/- SEM), 30.97 +/- 4.13% in JT, and 48.55 +/- 3.66% in OA to more than half of all cells in SS (67.2 +/- 3.1%). MIB-1 labeling was observed in 20.0 +/- 8.4% of SS cells., but only in 0.6 +/- 0.2% RA or < or = 1.1% in JT and OA SLCs. Mean AgNOR number per cell ranged from 2.9 +/- 0.1 in JT, 3.6 +/- 0.05 in OA and 4.3 +/- 0.3 in RA to 7.3 +/- 0.3 in SS. Significant differences were observed for Ki-67 and AgNORs, between SS and all other diseases and also between RA and OA (p < 0.01, U-test). In RA, Ki-67 was solely expressed in lymphocytes of germinal centres, but not in macrophages or PMN; in the lining layer expression of Ki-67 was only found in fibroblast-like cells. Our study confirms that T-cell or macrophage proliferation is rare in the RA SM. Also, the proliferation rates of fibroblast-like cells in the RA lining layer are rather low, in particular when compared to a sarcoma in the same anatomical location.