Autoimmune thyroid disease (AITD) is the most common organ-specific autoimmune disorder. Genetic background, environmental and endogenous factors are play important roles in determining the activation of immune cells or the efficacy of the immunoregulatory pathways. In recent years underlined the immunosuppressive role of T lymphocytes with expression of CD4+CD25+ (Tregs) in regulation mechanisms of peripheral immune tolerance.
The aim of the study was to estimate the expression of CD4+CD25high, CD4+ CD25+CD127low and CD4+FoxP3 T cells in patients with Graves disease (GD) (n=20, mean age 16.3 years old), in patients with Hashimotos thyroiditis (HT) (n=20, mean age 15.8 years old) in comparison with sex- and age-matched healthy control subjects (n=20, mean age 15.9 years old). The expression of the immune cells populations were analyzed by the four-color flow cytometry using a FACSCalibur (BD Biosciences) cytometer.
In untreated patients with Graves disease and HT we observed a significant decrease of CD4+FoxP3 (P<0.001, P<0.01) and CD4+CD25high (P<0.01, P<0.048) T lymphocytes in comparison to the healthy control subjects. The analysis of CD4+CD25+CD127low T cells in the peripheral blood revealed comparable percentages of these cells in patients with thyroid autoimmune diseases to the controls. In untreated Graves patients negative correlation between percentage of CD4+CD25high T cells and serum level of anti-TSH-R (P<0.017) antibodies was found, while no such correlation were detected in relation to CD4+CD25+CD127low or CD4+FoxP3 T cells.
We conclude that the defective function and the reduction number of Treg cells with expression of CD4+CD25high and CD4+FoxP3 could be responsible for loses immune tolerance and development of autoimmune process in thyroid disorders.
30 Apr - 04 May 2011
European Society of Endocrinology