T-cell subpopulations in the peripheral blood of patients with connective tissue diseases as determined by flow cytometry using monoclonal antibodies.

We studied by flow cytometry using monoclonal antibodies the T3, T4, and T8 subpopulations of T cells in the peripheral blood of 109 patients with various connective tissue diseases who were not receiving any treatment. Comparison of the results was made with those obtained with normal controls matched for age and sex with each connective tissue disease group. When compared as disease groups, patients with systemic lupus erythematosus (n = 41) had decreased T8 cells, but patients with active disease (n = 17) had all three T-cell subpopulations lower than their controls, whereas those with inactive disease (n = 24) showed no differences. Patients with rheumatoid arthritis (n = 23) had decreased T3 and T8 cells, whereas patients with scleroderma (n = 22) only had decreased T3 cells, and patients with primary Sjögren's syndrome (n = 15) had lower proportions of all three T-cell subpopulations than their matched controls. Patients with mixed connective tissue disease (n = 8) had proportions of all three T-cell subpopulations akin to those of their matched controls, but showed a tendency to have decreased T8 cells that reached statistical significance when compared to the entire control group. Although our findings tend to support the notion that the abnormalities in immunoregulatory T-cell circuits leading to autoimmunity are different in each connective tissue disease, the great variability found in both patients and controls seems to preclude the use of these determinations in individual patients for clinical purposes.