The stimulation of thyroid hormone secretion in vitro by thyroid-stimulating antibodies.

A new simple technique is described for the in vitro assay of thyroid-stimulating antibody (TSAb) in serum. Thyroid slices are incubated with serum in two-compartmental dialysis pot, followed by measurement of the thyroid hormone concentration in the dialysis fluid by RIA. Heat-inactivated normal serum applied directly to the tissue has no effect on the basal level of response. A dose-dependent relationship is demonstrated for both TSH and TSAb. Serum from patients with untreated Graves' hyperthyroidism is clearly shown to stimulate thyroid hormone secretion. Porcine thyroid tissue has been used and responds well to TSAb. This technique not only has the advantage of simple methodology, but also reflects the biological activity of TSAb. Therefore it will prove useful for further studies of the significance of TSAb and the pathogenesis of Graves' disease.