Simultaneous measurement of TSH-binding inhibitor immunoglobulin and thyroid stimulating autoantibody activities using cultured FRTL-5 cells in patients with untreated Graves' disease.
A new and practical assay was developed using cultured FRTL-5 cells for simultaneous assessment of TS-ab and TSH-binding inhibitor immunoglobulin, allowing direct comparison of these two activities under the same conditions. Subsequent to the TS-ab assay in which extracellular cAMP concentration in Hanks' medium without NaCl was determined, [125I]b TSH in this medium was added to observe the ability of serum Ig to inhibit the binding of [125I]b TSH to FRTL-5 cells. We found a much higher specific binding of [125I]b TSH to FRTL-5 cells and a much greater inhibition of [125I]bTSH binding to the cells exposed to Graves' Ig in hypotonic NaCl-free than in NaCl containing Hanks' medium, indicating that the binding of both TSH and Graves' Ig to the TSH receptor was salt-sensitive. The inhibitory activity of [125I]bTSH binding to the cells was 0.2 +/- 4.6% (mean +/- SD) in 45 normals. Inter-assay coefficients of variation in two positive controls with the mean values of 18.0 and 65.8% were 15.8 and 16.5%, respectively. Among 46 patients with untreated hyperthyroidism owing to Graves' disease, 45 (97.8%) were positive for TS-ab; 35 (76.1%) and 40 (87.0%) were positive for TSH-binding inhibitor in Ig assays using FRTL-5 cells and solubilized porcine thyroid membranes, respectively. TS-ab activities correlated less closely with TSH-binding inhibitory activities determined using FRTL-5 cells (r = 0.576, p less than 0.001) than with those determined using porcine thyroid membranes (r = 0.745, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
Lu
C
C
Department of Nuclear Medicine, Kyoto University School of Medicine, Japan.
Kasagi
K
K
Hidaka
A
A
Hatabu
H
H
Iida
Y
Y
Konishi
J
J
D001323:Autoantibodies / Q000032:analysis*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000096:biosynthesis; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating; D066298:In Vitro Techniques; D013696:Temperature; D013961:Thyroid Gland / Q000276:immunology; D013967:Thyroiditis, Autoimmune; D013972:Thyrotropin / Q000378:metabolism; D013997:Time Factors
D001323:Autoantibodies; D018828:Immunoglobulins, Thyroid-Stimulating; D013972:Thyrotropin; D000242:Cyclic AMP