LEUKOCYTE INFILTRATION IN SYNOVIAL TISSUE FROM THE SHOULDER OF PATIENTS WITH POLYMYALGIA - QUANTITATIVE-ANALYSIS AND INFLUENCE OF CORTICOSTEROID TREATMENT

Objective: To investigate the immunologic features of synovitis in pat ients with polymyalgia rheumatica (PMR) and to assess the modification s induced by corticosteroids. Methods. Arthroscopic biopsies of should er synovium were obtained from 12 patients with untreated PMR and from 7 patients with PMR that had been treated. Immunohistochemistry was p erformed on frozen sections utilizing a panel of monoclonal antibodies and computerized image analysis. Results. Synovitis was present in 10 of 12 (83%) untreated patients and in only 2 of 7 (29%) treated patie nts. The synovitis was characterized by vascular proliferation and leu kocyte infiltration. Infiltrating cells consisted predominantly of mac rophages and T Lymphocytes. Almost all T lymphocytes were CD45RO posit ive, A few neutrophils, but no B cells, natural killer cells, or gamma /delta T cells were found, Intense expression of HLA class II antigens (DR moreso than DP moreso than DQ) was found in the lining layer cell s as well as in macrophages and lymphocytes, DR, but not DP or DQ, was expressed by the endothelium of a few vessels, Class II antigen expre ssion correlated with the number of macrophages and lymphocytes, Macro phage infiltration of arteriole walls was observed in 1 untreated pati ent without giant cell arteritis (GCA), In untreated patients, there w as a positive correlation between the percentage of infiltrating T cel ls and the duration of disease. Steroid therapy was associated with a significant reduction in the number of blood vessels and of HLA class II expression, One treated patient who no longer had symptoms of PMR s till had active synovitis: a relapse occurred 4 months after the biops y. Conclusion. Our findings support the hypothesis that synovitis is a major cause of the musculoskeletal symptoms of PMR, There are immunol ogic similarities with the vascular inflammation observed in GCA, Cort icosteroids act on both the vascular and cellular components of synovi tis.