Comparison of the Level of DNA-Hydrolyzing Polyclonal IgG Antibodies in Sera of Patients with Hashimoto's Thyroiditis and Nontoxic Nodal Goiter.

Various catalytically active IgG antibodies or abzymes have been recently detected in the sera of patients with several autoimmune pathologies, where their presence is most probably associated with autoimmunization. Here we show for the first time that IgG from peripheral blood of patients with Hashimoto's thyroiditis and nontoxic nodal goiter possesses DNase activity. The properties of the DNase IgGs distinguished them from other known human DNases. The findings give an evidence in favor of the generation of polyclonal catalytic IgG by the immune system of individual patients with impaired function of the thyroid glands. The relative level of specific activity of IgGs in hydrolysis of DNA increases with the elevation of the relative amount of antibodies against thyroglobulin and with the decrease of thyroid hormone concentrations. All patients with hypothyroidism are characterized by a high level of catalytic antibodies, while elevation of functional activity of the thyroid gland and improvement of the clinical state of the patients lead to decrease of the antibody's enzymic activity.