CLINICAL USEFULNESS OF THYROID-STIMULATING ANTIBODY MEASUREMENT USINGCHINESE-HAMSTER OVARY CELLS EXPRESSING HUMAN THYROTROPIN RECEPTORS

Human thyrotropin (TSH) receptors were expressed in Chinese hamster ov ary (CHO) cells using eukaryotic expression plasmid pCXN2, which conta ins beta-actin promoter. We measured cAMP stimulation in CHO cells exp ressing human TSH receptors (CHO-hTSH-R cells) by immunoglobulin G (Ig G) of patients with Graves' disease and Hashimoto's thyroiditis, and c ompared the results with a conventional thyroid-stimulating antibody ( TS-Ab) assay using porcine thyroid cells and a TSH-binding inhibiting immunoglobulin (TBII) assay. Nineteen untreated patients with Graves' disease, including a case who developed hyperthyroidism after interfer on -alpha therapy for chronic hepatitis C, and 13 treated patients wit h Graves' disease, 10 patients with Hashimoto's thyroiditis and 8 cont rol subjects were studied. In 19 untreated patients with Graves' disea se, 17 patients showed positive CHO-hTSH-R cell stimulation, 11 patien ts showed positive porcine thyroid cell stimulation and 15 patients sh owed positive TBII. All the untreated patients showed positive results in at least one assay, Although significantly positive correlations w ere observed among CHO-hTSH-R cell stimulation, porcine thyroid cell s timulation and TBII activities, the IgG of several patients showed sig nificant discrepancy in the assay results. In a patient with interfero n-induced hyperthyroidism only CHO-hTSH-R cell stimulation was positiv e, while porcine thyroid cell stimulation and TBII were negative, Afte r the treatment with propylthiouracil for 6 months, CHO-hTSH-R cell st imulation became negative. The IgG of patients with Hashimoto's thyroi ditis did not show significant stimulation of CHO-hTSH-R cells. These results suggest that the CHO-hTSH-R cell stimulation assay is clinical ly useful for the diagnosis and follow-up of patients with Graves' dis ease.