Characterization of the optimal stimulatory effects of graves' monoclonal and serum immunoglobulin G on adenosine 3',5'-monophosphate production in fRTL-5 thyroid cells: a potential clinical assay.
Immunoglobulin G (IgG) preparations derived from the sera of patients with hyperthyroidism due to Graves' disease (TSAb) as well as a monoclonal IgG derived from heterohybridoma fusions of Graves' lymphocytes augmented cAMP levels in a continuous strain of functioning rat thyroid cells (clone FRTL-5) in culture. Optimal stimulation was the same for both types of IgG preparations when measured after 2 h of incubation with 5 X 10(4) cells/well and using cells maintained in a nongrowth, TSH-deficient medium for 7 days. At low IgG concentrations, the stimulatory activities of both preparations exhibited a linear dependence on concentration and similar Ka values (approximately 4 X 10(-8) M) despite the fact that 65% of the Graves' serum IgG preparations had a significantly better ability to inhibit TSH binding to membrane preparations. The Ka value for TSH in the same assay was about 5 X 10(-12) M. Using this cell assay, 90% of a series of hyperthyroid Graves' IgG preparations exhibited stimulating activity, a value comparable to the frequency of positive results found by ourselves and others using human thyroid cell and slice systems. In contrast, only 10% of patients who were euthyroid 1 yr after antithyroid drug withdrawal (n = 21) exhibited stimulating activity, and no stimulating activity was detected in patients with nontoxic nodular goiter (n = 11), toxic adenoma (n = 5), or thyroid carcinoma (n = 6). The studies suggest that an optimized rat FRTL-5 thyroid cell system is a clinically useful and convenient alternative to human thyroid cell and slice systems for detecting TSAbs.
D000818:Animals; D000906:Antibodies / Q000032:analysis*; D000911:Antibodies, Monoclonal; D001323:Autoantibodies / Q000032:analysis; D001681:Biological Assay / Q000379:methods; D002460:Cell Line; D000242:Cyclic AMP / Q000378:metabolism; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating; D051381:Rats; D013959:Thyroid Diseases / Q000276:immunology; D013961:Thyroid Gland / Q000187:drug effects*; D013972:Thyrotropin / Q000378:metabolism
D000906:Antibodies; D000911:Antibodies, Monoclonal; D001323:Autoantibodies; D018828:Immunoglobulins, Thyroid-Stimulating; D013972:Thyrotropin; D000242:Cyclic AMP