Suppressor cell function and t lymphocyte subpopulations in peripheral blood of patients with progressive systemic sclerosis

Three different in vitro assays—immunofluorescence with monoclonal anti‐T cell reagents, enumeration of Tγ cells, and nonspecific suppressor cell function—were used for the analysis of suppressor lymphocytes in the circulation of 28 patients with progressive systemic sclerosis (PSS, scleroderma) and 20 normal individuals. Both OKT8+ and Tγ lymphocytes were significantly reduced ( P < 0.001 and P < 0.02, respectively) in patients with PSS compared with controls. The OKT4/OKT8 ratio was increased ( P < 0.02). However, the mean suppressor cell index (SCI) of 1.9 (range 0.4‐6.6) for patients with PSS was not significantly different ( P > 0.05) from the SCI of 2.9 (range 1.2‐14) for controls. Eleven of the patients had depressed suppressor cell function as indicated by the index value of < 1.2. In only 5 of these patients, simultaneously measured Tγ and OKT8+ cells were reduced and OKT4+ lymphocytes were concomitantly increased. There were no significant correlations between the numbers of Tγ or OKT8+ cells and the SCI in patients and controls. Neither depressed suppressor cell function nor the OKT4+/OKT8+ ratio > 4.2 (>2 SD of normal) in the patients could be related to other immunologic findings, to disease duration and severity, or to involvement of internal organs. These results suggest that depressed suppressor cell activity and immunoregulatory T cell imbalance in PSS may not be directly related to the pathogenesis of the disease.