Thyrotrophin-binding-inhibition assay: comparison of crude and purified membrane preparations.
Two different thyroid membrane preparations (TMP), crude and pure, made from a homogenate of normal human thyroid tissue, were used to test purified serum IgG from 36 patients with Graves' disease, and 10 normal control subjects, in the thyrotrophin-binding-inhibition (TBI) assay. All reagents for the assay were identical, and aliquots of each IgG were tested in both TMP simultaneously, under exactly comparable conditions. Blood was drawn while the patients were hyperthyroid (19), euthyroid (13), or hypothyroid (4); 15 of the patients were untreated and 21 were being treated. The frequency of positive TBI was similar in both TMPs and highest among the 131I-treated patients. Comparison of TBI results in both TMP for each IgG sample revealed wide differences, and 47.1% of the Graves' IgGs were TBI positive in one membrane preparation, while negative in the other. There was no correlation of TBI values between the two TMP, or with clinical status, or the presence of standard thyroid antibodies. The findings indicate that the IgGs of Graves' disease, as now tested in the TBI assay, bind heterogeneous to different fractions of the thyroid membranes.
D001666:Binding Sites, Antibody; D002462:Cell Membrane / Q000378:metabolism; D006111:Graves Disease / Q000276:immunology* / Q000378:metabolism; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D011956:Receptors, Cell Surface / Q000378:metabolism; D011989:Receptors, Thyrotropin; D013961:Thyroid Gland / Q000378:metabolism*; D013972:Thyrotropin / Q000378:metabolism*
D007074:Immunoglobulin G; D011956:Receptors, Cell Surface; D011989:Receptors, Thyrotropin; D013972:Thyrotropin