These authors contributed equally to the paper.
Novel chimeric thyroid-stimulating hormone-receptor bioassay for thyroid-stimulating immunoglobulins
Article first published online: 10 NOV 2010
© 2010 The Authors. Clinical and Experimental Immunology © 2010 British Society for Immunology
Clinical & Experimental Immunology
Volume 162, Issue 3, pages 438–446, December 2010
How to Cite
Lytton, S. D., Li, Y., Olivo, P. D., Kohn, L. D. and Kahaly, G. J. (2010), Novel chimeric thyroid-stimulating hormone-receptor bioassay for thyroid-stimulating immunoglobulins. Clinical & Experimental Immunology, 162: 438–446. doi: 10.1111/j.1365-2249.2010.04266.x
Note: The FDA-cleared TSI-Mc4 bioassay is now commercially available (Thyretain™).
- Issue published online: 10 NOV 2010
- Article first published online: 10 NOV 2010
- Accepted for publication 20 August 2010
- cell-based assay;
- chimeric TSH receptor;
- luciferase reporter;
- thyroid-stimulating immunoglobulins
Thyroid-stimulating immunoglobulins (TSI) are a functional biomarker of Graves' disease (GD). To develop a novel TSI bioassay, a cell line (MC4-CHO-Luc) was bio-engineered to constitutively express a chimeric TSH receptor (TSHR) and constructed with a cyclic adenosine monophosphate (cAMP)-dependent luciferase reporter gene that enables TSI quantification. Data presented as percentage of specimen-to-reference ratio (SRR%) were obtained from 271 patients with various autoimmune and thyroid diseases and 180 controls. Sensitivity of 96% and specificity of 99% for untreated GD were attained by receiver operating characteristic analysis, area under the curve 0·989, 95% confidence interval 0·969–0·999, P = 0·0001. Precision testing of manufactured reagents of high, medium, low and negative SRR% gave a percentage of coefficient-of-variation of 11·5%, 12·8%, 14·5% and 15·7%, respectively. There was no observed interference by haemoglobin, lipids and bilirubin and no non-specific stimulation by various hormones at and above physiological concentrations. TSI levels from GD patients without (SRR% 406 ± 134, mean ± standard deviation) or under anti-thyroid treatment (173 ± 147) were higher (P < 0·0001) compared with TSI levels of patients with Hashimoto's thyroiditis (51 ± 37), autoimmune diseases without GD (24 ± 10), thyroid nodules (30 ± 26) and controls (35 ± 18). The bioassay showed greater sensitivity when compared with anti-TSHR binding assays. In conclusion, the TSI-Mc4 bioassay measures the functional biomarker accurately in GD with a standardized protocol and could improve substantially the diagnosis of autoimmune diseases involving TSHR autoantibodies.