Stimulated iodide uptake in FRTL-5 cells preincubated with Graves' immunoglobulins in NaCl-free medium: a sensitive assay for thyroid-stimulating antibodies.
The present study was designed to increase the sensitivity of iodide uptake assay for detecting thyroid-stimulating antibodies (TSAb). Based on the previous observations that TSAb are more active to increase cAMP levels in the NaCl-free condition, we improved the assay procedure and defined the optimum conditions: FRTL-5 cells were incubated with immunoglobulin (IgG) in NaCl-free medium for 3 days, and then 125I uptake in the cells was determined after 60 min. The sensitivity of iodide uptake assay for TSAb increased 3-fold by the modification, when assessed by the IgG concentration required to elicit the same response. The described assay is as sensitive as that using cAMP measurement in NaCl-free buffer. Thus, it could detect TSAb in all 21 patients with active Graves' disease and in 7 of 8 with ophthalmic Graves' disease but not in 29 of 30 control subjects. Thyroid stimulating activities assessed by these two assays correlated with each other (n = 29, r = 0.707, p < 0.001). False positive results obtained in 4 hypothyroid patients with Hashimoto's thyroiditis (serum TSH concentrations, 11-171 mU/L) could be prevented using anti-TSH antibodies. In summary, the described assay allows evaluation of stimulated thyroid function directly without affecting the detection of TSAb.
Hidaka
A
A
Department of Nuclear Medicine, Kyoto University School of Medicine, Japan.
Kasagi
K
K
Takeuchi
R
R
Iida
Y
Y
Misaki
T
T
Grollman
E F
EF
Konishi
J
J
D000818:Animals; D001323:Autoantibodies / Q000032:analysis*; D001681:Biological Assay / Q000379:methods / Q000706:statistics & numerical data; D002460:Cell Line; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis; D018828:Immunoglobulins, Thyroid-Stimulating; D007454:Iodides / Q000493:pharmacokinetics*; D007457:Iodine Radioisotopes; D017136:Ion Transport / Q000187:drug effects; D051381:Rats; D012680:Sensitivity and Specificity; D012965:Sodium Chloride; D013961:Thyroid Gland / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D013967:Thyroiditis, Autoimmune / Q000097:blood / Q000276:immunology; D013972:Thyrotropin / Q000494:pharmacology
D001323:Autoantibodies; D003470:Culture Media; D007074:Immunoglobulin G; D018828:Immunoglobulins, Thyroid-Stimulating; D007454:Iodides; D007457:Iodine Radioisotopes; D012965:Sodium Chloride; D013972:Thyrotropin; D000242:Cyclic AMP