TSH Receptor Autoantibodies Affecting Thyroid Cell Function

Abstract

Autoantibodies directed to different components of the thyroid cell are present in sera of patients with thyroid autoimmune disorders (1). Among the thyroid cell, structures, the TSH receptor has been implicated as the putative antigen of autoantibodies having different biological effects. Autoantibodies able to mimic TSH in its ability to stimulate thyroid hormone production and cell growth have been found in sera of patients with Graves’ disease and in minority of those with other thyroid autoimmune disorders (2). Furthermore it was observed that the IgG fraction from the same patients inhibited the binding of radiolabeled TSH to its receptor. More recently, autoantibodies able to inhibit some biological effects of TSH on the thyroid cell were found in sera of patients with idiopathic myxedema. These antibodies may be important in the pathogenesis of thyroid atrophy and hypothyroidism (3, 4). Thus, several data suggest that autoantibodies from patients with thyroid autoimmune diseases may either mimic or block the TSH action on the thyroid cell. In the present review we report the incidence and the biological effects of these antibodies detected by different assays using human thyroid cell membranes and FRTL-5 thyroid cells.