title: Interaction between thyroid-stimulating immunoglobulins and thyrotropin receptors in fat cell membranes.
abstract: In the TSH radioreceptor assay to study the interaction between Graves' immunoglobulins (Ig) and TSH receptors in guinea pig fat cell membranes, Graves' Ig were found to inhibit [125I]TSH binding to fat cell membranes in a dose-dependent manner. Scatchard analysis of [125I]TSH displacement curves by Graves' Ig indicated a single population of the binding sites in fat cell membranes, in contrast to two populations of TSH-binding sites in the membranes. Displacement of [125I]TSH bound to fat cell membranes by both Graves' Ig and unlabeled TSH were time and temperature dependent, with similar dissociation curves, suggesting a specific binding of Graves' Ig to the membrane sites related to the TSH receptor in the fat cells. Such Ig are referred to as fat cell-binding Ig, to be distinguished from the thyroid-stimulating Ig (TSI) detected by TSH radioreceptor assay using human thyroid membranes. Both fat cell-binding Ig and TSI were detected in the sera of a great majority of untreated patients with Graves' disease. A significant correlation was found between both values (r = 0.80; n = 19; P less than 0.001). According to these results, TSI might represent an autoantibody to the membranes associated with the TSH receptor of the target tissues without a strict organ specificity.
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D006111:Graves Disease / Q000276:immunology*; D006168:Guinea Pigs; D006801:Humans; D007118:Immunoassay; D007136:Immunoglobulins; D007700:Kinetics; D008297:Male; D011869:Radioligand Assay; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism*
chemical_list: D007136:Immunoglobulins; D011956:Receptors, Cell Surface; D013972:Thyrotropin