AN IMPROVED RADIORECEPTOR ASSAY FOR TSH RECEPTOR ANTIBODIES

Abstract

An improved receptor assay for TSH receptor antibodies is described in which detergent-solubilized TSH receptors and 125I-labeled TSH are used. Normal human serum and ig concentrates from normal serum showed little effect on the interaction between labeled TSH and detergent=solubilized receptors while ig concentrates from some Graves'' sera caused marked inhibition of TSH binding. Precipitation with polyethylene glycol was the most convenient way of preparing ig concentrates and using this technique the assay could be completed in a few hours. The coefficient of inter assay variation at 51% inhibition of labeled TSH binding was 3.7% and analysis of serum samples from patients with Graves'' disease (n = 42), Hashimotos disease (n = 26), multinodular goiter (n = 9), rheumatoid arthritis (n = 10) and normal donors (n = 35) suggested that the assay could detect TSH receptor antibodies in about 80% of patients (treated and untreated) with Graves'' disease.