ESPE Abstracts

Background: Graves’ disease (GD) is almost always the cause of hyperthyroidism in children. Studies carried out for recent years confirm an important role of T regulatory cells (Tregs) in the development of autoimmune diseases. However, the interactions between T-cell response and Treg proliferation in GD is still poorly understood.

Objective and hypotheses: The aim of this research was the assessment of the in vitro proliferation of Treg cells and T CD3+ lymphocytes in 50 children with GD before and after the treatment with methimazole (MMI).

Methods: The study was conducted by means of a proliferation test which uses methyl-3H-thymidyne. The relations between proliferation assays and selected clinical parameters were also described.

Results: T CD3+ and T CD3+ with PMA lymphocyte proliferation rates before the treatment with MMI were significantly higher than after the treatment (P<0.0001). Treg and Treg with PMA cell proliferation rates were significantly lower before the treatment (P<0.0001). Moreover, we observed higher Treg (P<0.0001) and Treg with PMA (P<0.05) cell proliferation rates before the treatment as well as after the treatment in patients who had no relapse of hyperthyroidism. There was also observed a positive correlation between CD3+ lymphocyte proliferation rate before the MMI treatment and FT₃ as well as FT₄ concentration (r=0.839, P<0.0001 and r=0.375, P<0.01, respectively). Then T CD3+ lymphocyte proliferation rates before and after the treatment with MMI were positively correlated with TSI (r=0.968, P<0.0001 and r=0.522, P<0.0001, respectively).

Conclusions: Co-cultures of Tregs and T CD3+ cells show that Tregs are not capable of inhibiting efficiently the proliferation of T CD3+ cells in these patients. Partly dysfunctional in Graves’ disease Tregs seem to be suppressed by CD3+T cells. Our observations indicate that MMI treatment helps Treg cells to restore their suppressive function in autoimmune diseases indicating some immunomodulatory effects of methimazole.