Direct Evidence for Human Thyroidal Stimulation by LATS-Protector

To examine the hypothesis that LATS-protector may cause thyroidal hyperfunction in Graves' disease, the effect of LATS-protector on the intracellular colloid droplet formation in human thyroid tissue was studied in vitro. The IgG's from 9 untreated patients with Graves' disease, 4 thyrotoxic patients who were being treated hut were still thyrotoxic, and 4 normal subjects not showing LATS were chosen to study the presence of LATS-protector and its human thyroid stimulating activity. LATS-protector was assayed as described by Adams with slight modifications. LATS-protector was demonstrated in the IgG's of 6 out of 9 untreated patients with Graves' disease. Their IgG significantly inhibited the inactivation of LATS by the thyroid extract, recovering approximately 30% of the LATS-potency. The IgG from the treated, but thyrotoxic patients or from the normal individual did not show such an inhibition. When sliced normal human thyroid tissue was incubated with the IgG from thyrotoxic patients, an obvious elevati...