The Prevalence and Characteristics of Allergy in Autoimmune Thyroid Diseases

Objective: The relationship between autoimmunity and allergy is well known. The immunoregulation can be modified towards T helper 2 dominance by cytokines and regulatory T cells, which participate in both diseases. Autoimmune thyroid diseases possess different immunoregulatory and sympathoadrenal activity, whose features can be reflected by their association with allergic attacks and the degree of allergen-specific IgE levels. Methods: Two-hundred-fifty-nine patients, 149 with Graves’ disease (57 had ophthalmopathy), 110 with Hashimoto’s thyroiditis and 65 controls with small euthyroid goitre were investigated. Allergen-specific IgE levels to 20 respiratory and 20 food allergens were detected by AllergySreen immunoblot method and given in IU/ml. Thyroid hormones and autoantibodies to thyroid peroxidase (TPO) and thyroglobulin (Htg) were measured in a fully automated way, but TSH receptor antibodies with radioimmunoassay. Results: The prevalences of respiratory and food allergen-specific IgE levels were higher in Graves’ disease in comparison with Hashimoto’s thyroiditis and controls. The seasonal allergen-specific IgE levels increased more in Graves’ patients without ophthalmopathy, than in patients who had eye symptoms and Hashimoto’s thyroiditis. Mugwortand soybean-specific IgE levels elevated significantly in the absence of anti-Htg and the presence of TSH receptor antibodies, respectively. In turn, the presence of allergen-specific IgE levels was associated with alterations in thyroid hormone and antithyroid antibody levels too. Conclusion: The elevated prevalences of respiratory and food allergies reflected Th2-derived cytokine productions in autoimmune thyroid diseases. The lower respiratory and food allergen-specific IgE levels highlighted a role of prominent proinflammatory cytokine productions in Graves’ ophthalmopathy and Hashimoto’s thyroiditis. Allergy due to increased Th2-derived and proinflammatory cytokine productions may aggravate or induce AITDs, as well as via modified thyroid hormone and antithyroid antibody levels may contribute to a slow remission rate of Graves’ hyperthyroidism.