Effect of methimazole treatment for 2 years on circulating IL-4, IgE, TBII, and TSAb in patients with hyperthyroid Graves' disease

In this study we confirmed our previous findings on the importance of IgE in Graves' disease and further investigated the relationships existing among Graves' disease, IgE, and interleukin-4. Two hundred and thirty-two newly diagnosed Graves' disease patients were treated with methimazole for 2 years, and were classified into 3 groups according to their response to the therapy. Incidence of IgE elevation (IgE> or =170 IU/ml) before treatment was lowest, 23.8%, in the group who achieved remission without recurrence, while it was 41.7% in the group who achieved remission but recurrence occurred within 4 years. Incidence of IgE elevation before treatment was highest, 60.7%, in the group who failed to achieve remission, significantly higher than that of the group without recurrence. Incidence of IgE elevation before treatment in all these patients of Graves' disease were 35.3%, significantly higher than those of Hashimoto's thyroiditis (17.5%) and of simple goiter (7.0%). Serum IL-4 levels before treatment were significantly higher in the patients of Graves' disease with IgE elevation than in those without IgE elevation. Serum T4 concentration and TSAb titration before treatment were also significantly higher in elevated IgE group than in normal IgE group. These results support our previous findings and suggest that IL-4 may play important roles in the elevation of IgE, TBII, and TSAb in patients of Graves' disease, and that IL-4 and IgE may be involved in the development, progression, and maintenance of Graves' disease.