Regulatory T cells in peripheral blood of patients with mixed connective tissue disease

Objective: To determine the percentage and absolute number of CD4(+) regulatory T-cells ( Treg) in 48 patients with mixed connective tissue disease ( MCTD). Methods: Data were classified on the basis of the stage of the disease: 17 patients were in the active stage and 31 in the inactive stage. The absolute number of CD4(+)/ intracellular interleukin- 10(+) (IL-10(+)) and CD4(+) CD25(+) high Treg cells was determined by flow cytometry. The percentage of CD4+ CD25+ high suppressor T- cells was determined on the basis of Foxp3 expression. Results: The percentage and the absolute number of CD4+ CD25+ high Treg cells were lower in patients than in healthy controls (p < 0.04), and were further decreased in patients with active MCTD and were lower than in the inactive stage (p < 0.01). There was an increase in the percentage and absolute number of CD4(+) IL-10(+) Treg cells in patients with MCTD compared to the healthy controls ( pv0.02). The percentage of CD4+ IL- 10+ Treg cells was higher in the active stage of MCTD than in the inactive stage of the disease (p < 0.005). However, we did not find any significant difference in the absolute number of CD4(+) IL-10(+) Treg cells between the patients in the active and inactive stages of MCTD. Conclusion: Our results suggest that the decrease in the number of CD4(+) CD25(+) high Treg cells in an important factor in the immunoregulatory disturbance in patients with MCTD. We suggest that the increase in the number of CD4(+) IL-10(+) Treg cells is a compensatory mechanism aiming to restore the balance between type 1 and type 2 cytokines in MCTD.