ESPE Abstracts

Introduction: The incidence of autoimmune thyroid diseases (ATD) is constantly rising. Graves’ disease (GD) remains the most common cause of thyrotoxicosis in pediatric population, but the exact pathogenesis of GD is still not fully understood. The immunological basis of ATD assumes an imbalance between effector and regulatory T lymphocytes. B regulatory cells (Breg) are able to suppress the pro-inflammatory properties of effector T cells. Methimazole (MMI) is preffered drug to treat GD in children.

Aim: The aim of this investigation was to analyze distribution of chosen effector T cells and to evaluate a potential correlation between effector T cells and Breg in GD pediatric patients. We also tried to explore effects of MMI therapy on the level of those groups of cells.

Material and Methods: A total of 22 pediatric patients with GD diagnosis were involved in the study. The control group consisted of 31 euthyroid healthy children. Peripheral blood was collected from GD patients at the admission and after initiation of MMI therapy. 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 effector T cells (precisely Th1, Th17 and Th22 subpopulations) in GD patients at the diagnosis. Interestingly, there was no significant difference in cells populations in the course of MMI therapy. We also observed loss of dependency between T effector and B regulatory cells in GD patients compared to healthy controls.

Conclusions: Our study confirms that the correct immune responses are ensured by a constant interplay between effector and regulatory cells and any disturbance of this balance may result in autoimmunity. These results may be used as a field to find new treatment methods.