To understand better the role that immune mechanisms could play in the pathogenesis of progressive systemic sclerosis (PSS), the phenotypes of peripheral blood lymphocytes (PBL) from 24 PSS patients and normal controls were compared by a panel of monoclonal antibodies. PBL T cells of patients expressed an increased percentage of several activation markers as defined by monoclonal antibodies B33.1 (anti-Ia), TAC (anti-interleukin 2 receptor) and 5E9 (anti-transferrin receptor). These antigens were also found on PBL of patients with quiescent disease suggesting the persistence of an ongoing immune response despite the absence of clinically apparent disease activity. Patients treated with D-penicillamine had uniformly normal proportions of Ia+ T cells (less than 5%) although the percentage of cells positive for Tac and transferrin receptor continued to be elevated. A second finding was that the percentage of natural killer (NK) cells studied with the monoclonal antibody against NK cells B73.1 (Leu 11c) and particularly an OKT8+ NK cell subset was low in patients (10.4 +/- 4.7) compared with controls (15.9 +/- 5.8). Finally, both treated and untreated patients displayed increased OKT4+/OKT5+ ratios compared to controls. These data suggest that PBL from PSS patients are activated and have abnormal proportions of cell subpopulations. These abnormalities are also present in patients with quiescent disease. The observed effect of D-penicillamine on Ia expression in PSS PBL may reflect a mechanism of action of this drug in the control of autoimmune diseases
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