Activation of membrane-bound adenylcyclase by thyroid stimulating antibodies

Human thyroid plasma membranes isolated from thyroids from patients with Graves' disease or non-toxic nodular goitres produced, under basal conditions, about 100 pmol cAMP per mg membrane protein in 30 min at 37 degrees C. TSH increased the membrane response from a Graves' thyroid by up to 11-fold. cAMP production with immunoglobulins from patients with Graves' disease was four times that from normal immunoglobulins. The onset of action of thyroid stimulating antibodies (TSAb) was rapid and persisted for 30 min of incubation. A change of incubation buffer from 20 mM to 200 mM Tris-HCl reduced the degree and altered the pattern of immunoglobulin stimulation, whereas maximal TSH stimulation was unchanged. The in vitro interaction between the TSH receptor system and TSAb or TSH will differ according to the conditions used.