Analysis of changes in the percentage of B (CD19) and T (CD3) lymphocytes, subsets CD4, CD8 and their memory (CD45RO), and naive (CD45RA) T cells in children with immune and non-immune thyroid diseases.

Graves' disease (GD) is an autoimmune thyroid disease caused by immunological abnormality. The immune cells (lymphocytes T and B) which infiltrate the thyroid gland play a key role in the development of autoimmune thyroid disease (AITD). The aim of this study was to evaluate the differences between distribution of T (CD3) lymphocytes, subsets CD4, CD8, and their memory (CD45RO), and naive (CD45RA) T cells and B (CD19) lymphocytes in the peripheral blood of patients with Graves' disease (GD) (n = 33, mean age 15.9 +/- 5.9 years) and non-toxic nodular goiter (NTNG) (n = 25, mean age 15.2 years), in comparison to age- and sexmatched healthy control subjects (n = 25, mean age 15.9 years). The percentages of peripheral blood lymphocyte subsets were analyzed by three-color flow cytometry using a Coulter EPICS XL cytometer. In the untreated Graves' patients we observed an increase in the percentage of CD19+ (p<0.007, p<0.003), CD4+ (p<0.004, p<0.017), CD4+CD45RO+ (p<0.04, NS), CD4/CD8 ratio (p<0.002, p<0.001) and a decrease in the percentage of CD8+ (p<0.02, p<0.02), CD4+CD45RA+ (p<0.04, p<0.03) cells in comparison to the healthy control subjects and euthyroid Graves' patients. These abnormalities were absent in children with non-toxic nodular goiter. In addition, the levels of CD3+, CD4+CD8+, CD8+CD45RO+ T cells and CD8 lymphocytes co-expressing CD45RA and CD45RO antigens were similar in all groups and no statistically significant differences were found in comparison to the healthy controls. In the untreated Graves' patients we found a positive correlation between serum levels of fT4 and fT3 and the percentage of CD19+ lymphocytes (r = 0.45, p<0.01, r = 0.37, p<0.04), between serum level of fT4 and the percentage of CD4CD45RO (r = 0.4, p<0.02) lymphocytes and between concentration of TRAb and CD4+ (r = 0.38, p <0.04) and CD19+ (r = 0.39, p<0.016) cells. Statistically significant negative correlations existed between TRAb, TPO-Ab or TG-Ab concentration in blood serum and the percentage of CD8+ lymphocytes (r = -0.55, p<0.002; r = -0.41, p<0.02; r = -0.51, p<0.004), and between fT4 concentration and the percentage of CD8+ (r = -0.39, p<0.02) lymphocytes. No such correlation was detected in patients with non-toxic nodular goiter. We conclude that the abnormal distribution of B lymphocytes, memory and naive T cell subsets in the peripheral blood in children and adolescents with untreated Graves' disease suggests their role in the development of autoimmunity. The normalization in the percentage of these immune cells after thyrostatic treatment in comparison to newly diagnosed patients confirms the immunomodulatory effect of methimazole therapy.