Endocrine Abstracts

Up till now, altered balance of T helper 1 (Th1) and Th2 immune cells has been postulated to play an important role in the pathogenesis of autoimmune thyroid diseases (AITD). However, recent studies on thyroid diseases suggest a new role for Th17 (T helper 17) cells which have the ability to secrete cytokines: IL17, IL17F, IL21, and IL23. The aim of the study was to estimate the proporcions of circulating CD4+CD161+CD196+ and CD4+IL17+ Th17 cells and serum concentrations of IL17 and IL23 in patients with Graves’ disease (GD, n=42, mean age±S.E.M. 14.3±4 years), Hashimoto’s thyroiditis (HT, n=37, mean age±S.E.M. 15±2 years) and in healthy controls (C, n=25, mean age±S.E.M. 15.2±2 years).

Polychromatic flow cytometry and several fluorochrome-conjugated MAbs were applied to delineate Th17 cells using apparatus FACSCalibur (BD Biosciences).

In untreated HT children we observed an increased percentage of CD4+CD161+CD196+ (7.1±3.5 vs 3.7±1.8; P<0.04) and CD4+IL17+ (3.7±2.7 vs 1.4±0.4; P<0.01) Th17 lymphocytes in comparison to the healthy controls. In GD children we did not reveal such abnormalities in the population of these cells. In untreated patients with AITD we observed an increased levels of IL23 in comparison to control group (GD: P=0.004 and HT: P=0.046). Methimazole treatment in GD led to decrease these cytokine levels in a period of 6–12 months. However, during 6–24 months of l-thyroxine therapy in HT there wasn’t any reduction of IL23 concentration compared with HC. IL17 was elevated only in HTpatients in comparison to the controls (17.17±10.49 vs 11.38±2.99, P=0.021), which normalized during therapy. We conclude that the increased percentage of Th17 cells and elevated level of IL17 and IL23 cytokines in children with HT can suggest their role in initiation and development of immune and inflammatory processes in this endocrinopathy.