impact of immunoglobulin E serum levels on clinical presentation and immunological status in graves' hyperthyroidism

ABSTRACT

There is growing evidence pointing to the involvement of IgE in the pathogenesis of Graves' disease. Despite this evidence, the diagnostic significance of IgE in Graves' hyperthyroidism is still not established. Therefore, forty-six patients with hyperthyroid Graves' disease were studied together with twenty patients with toxic nodular goiter and 25 age and sex matched healthy subjects. Quantitative estimation of IgE. antithyroid perioxidase [Anti-TPO] and antithyroglobulin [Anti-Tg] were analyzed by sandwich ELISA. Peripheral blood CD3+, CD4+ and CD8+ were analyzed by direct immunoflourescence. Natural killer activity was measured by a standard 4-hour Cr[51] releasing assay. The data of the present study revealed significant elevation of IgE, Anti-TPO and Anti-Tg antibodies in hyperthyroid Graves' disease [196.54 +/- 199.4 IU/ml, 219.3 +/- 66.41 lU/ml and 278.8 +/- 86.51 IU/ml respectively] than in toxic nodular goiter [49.4 +/- 51.97 IU/ml, 57.15 +/- 13.29 IU/ml and 116.55 +/- 67.94 IU/ml respectively] or control subjects [44.32 +/- 43.4 IU/ml. 50.32 +/- 10.07 IU/ml and 94.8 +/- 10.79 IU/ml respectively]. Hyperthyroid Graves' patients with IgE elevation had increased incidence of ophthalmopathy, increased clinical and biochemical severity of the disease and increased thyroid autoantibodies titres together with reduced natural killer activity in comparison to patients with normal lgE serum levels. Graves' patients with clinically evident ophthalmopathy had significantly higher levels of IgE, Anti-TPO and Anti-Tg antibodies besides reduced natural killer activity than those without ophthalmopathy. From this study, it is concluded that IgE determination in hyperthyroid Graves' disease could define a subgroup of patients with altered clinical and immunological profiles. Hyperthyroid Graves' patients with ophthalmopathy have more marked immunological changes despite nonsignificant differences in clinical or biochemical severity of the disease in comparison to patients without ophthalmopathy