The assay for thyroid stimulating immunoglobulin using cultured human thyroid cells and its clinical application.

A new technique for the determination of the serum level of thyroid stimulating immunoglobulins (TSI) is described. TSI may be detected by measuring cyclic AMP increases in cultures of isolated thyroid epithelial cells in response to added normal or patient's serum. Our results showed that the serum level in the normal control group was mostly lower than 110%, however, in 9.1% of normal human sera, TSI showed a positive result. In abnormal position, activity of TSI was higher than 110% of the rate of the normal control group. The positive result was 86% and the serum TSI levels were 270 +/- 176.6% in patients with Graves' disease before receiving antithyroid drug. After treatment with antithyroid drugs from one to thirty months, the positive results dropped to 35% and the serum TSI level decreased to 117.0 +/- 113%, which was significantly lower than that in untreated patients. In conclusion, TSI can be detected in the majority of the sera in patients with Graves' disease using this technique. It is helpful to the diagnosis and treatment of the Graves' disease.