Open AccessDevelopment of a Luminescent Bioassay for Thyroid Stimulating Antibodies
Author(s) -
Carol Evans,
Nils G. Morgenthaler,
S. Lee,
David H. Llewellyn,
Roderick CliftonBligh,
Robert A. John,
John H. Lazarus,
Krishna Chatterjee,
Marian Ludgate
Publication year - 1999
Publication title -
the journal of clinical endocrinology and metabolism/journal of clinical endocrinology and metabolism
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.206
H-Index - 353
eISSN - 1945-7197
pISSN - 0021-972X
DOI - 10.1210/jcem.84.1.5532
Subject(s) - bioassay , medicine , antibody , receptor , endocrinology , thyroid , thyrotropin receptor , luciferase , clone (java method) , chemistry , graves' disease , immunology , biology , biochemistry , transfection , gene , genetics
The hyperthyroidism of Graves Disease (GD) is due to thyroid stimulating antibodies (TSAb) which are thyrotropin (TSH) agonists. They are detected routinely by measuring their ability to inhibit TSH binding to the receptor (TBII), which does not reflect their true biological activity. Current bioassays which measure cAMP by RIA, are not suitable for routine use. We have developed a luminescent bioassay for TSAb, by introducing a cAMP responsive luciferase construct into CHO cells stably expressing the human TSH receptor (TSHR). Clone lulu1 displays dose dependent TSH response detectable from 10 μU/ml and maximal at 10 mU/ml when a >25 fold increase in light output is obtained. 34 euthyroid sera were tested to determine a reference range, with values >1.5 relative light units (R.L.U.) being considered positive. An international TSAb standard responded in a dose dependent manner with 10 mIU/ml giving an R.L.U. of >10. The assay was adapted to a 96 well format for automatic readout and 100 treated GD samples (50 TBII negative and 50 TBII positive) were tested, 73% being positive. In contrast only 4% of 79 control sera from individuals with Hashimoto’s, non-thyroid autoimmunity or multinodular goitre produced R.L.U. >1.5. When 44 of the GD sera were compared in a traditional salt-free bioassay, 61% were positive compared with 75% in the new luminescent assay. In conclusion, we have developed a luminescent bioassay for TSAb, using unfractionated serum which is capable of high throughput suitable for routine use.