Autoantibodies Stimulating Thyroid Growth and Adenylate Cyclase Cannot be Separated in IgGs From Patients with Active Graves’ Disease

Abstract

Previous studies have shown that immunoglobulin G (IgG) able to stimulate thyroid adenylate cyclase (TSAb) or growth (TGSAb) are present in sera of patients with active Graves 1 disease. The guestion of whether these two effects are produced by the same or different IgG is still under investigation. Valente et al. (1) reported that the stimulation of adenylate cyclase and growth were two separate bioeffects of TSH, and that TGSAb and TSAb could be independently found in patients with thyroid autoimmune disorders (2). Moreover, in patients with nontoxic goiter, other authors reported that TGSAb could be detected by a cytochemical assay in the absence of any adenylate cyclase stimulatory activity (3).It is worth noting that in all these studies TGSAb and TSAb were measured in separate assays, under different assay conditions. To further investigate the relationship between TSAb and TGSAb we have developed an assay for simultaneous measure of TSAb and TGSAb using FRTL-5 cells.TSAb were detected by their ability to stimulate I~ uptake, a direct conseguence of cAMP stimulation; TGSAb were measured by a 3 H-thymidine incorporation assay.In the present study we report the results obtained in patients with active Graves’ disease.