ESPE Abstracts

Introduction: The precise pathogenesis of Graves’ disease (GD) still remains unclear, especially in the field of immunological aspects. Thyroid infiltration by reactive T and B lymphocytes plays a crucial role in the course of autoimmune thyroid diseases (ATD). Previous pattern of inflammation process was characterized by the presence of two antagonistic groups of T effector or also called- helper cells: Th1 and Th2. Recently, more attention is paid to Th17, relatively newly developed Th22 and B regulatory cells (Breg). This subject is rarely undertaken in the context of the children population.

Aim: The aim of this study was to analyze differences in level of Th1, Th17 and Th22 and assess correlation between T effector and B regulatory cells (Breg) in GD pediatric patients. Additionally, we explored effects of therapy with methimazole on these populations.

Material and methods: A total of 22 children with active GD were involved in the investigation. The control group consisted of 31 euthyroid healthy children. Peripheral blood was collected from GD patients at three time-points: at the admission (before treatment), after 3 months and 1 year of the methimazole implementation. The expressions of the immune cell populations were analysed by four-color flow cytometry using a FASC Canto II cytometer (BD Biosciences).

Results: We reported higher levels of Th1, Th17 and Th22 within CD4+ lymphocytes and as absolute cell numbers in GD patients at the diagnosis. There was no significant difference in cells populations in the course of anti-thyroid treatment. Furthermore, we found positive correlation between levels of Th17 and Th22 and higher fT3 concentration before therapy initiation. Finally, we observed decline of mutual dependencies between T helper cells and B regulatory cells in GD patients compared to healthy controls, where there is a balance of pro- and anti-inflammatory lymphocytes.

Conclusions: Our data discusses the potential role of chosen subsets of T effector and B regulatory cells in pediatric GD development. Presented results confirm that in the course of ATD, immunological homeostasis is disturbed and certain lymphocytes are superior to others what may be used as a ground for new treatment options in the future.