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 (p<0.02). 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.