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 T gamma 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 T gamma lymphocytes were significantly reduced (P less than 0.001 and P less than 0.02, respectively) in patients with PSS compared with controls. The OKT4/OKT8 ratio was increased (P less than 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 greater than 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 less than 1.2. In only 5 of these patients, simultaneously measured T gamma and OKT8+ cells were reduced and OKT4+ lymphocytes were concomitantly increased. There were no significant correlations between the numbers of T gamma or OKT8+ cells and the SCI in patients and controls. Neither depressed suppressor cell function nor the OKT4+/OKT8+ ratio greater than 4.2 (greater than 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.