Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2008) 16 P819

ECE2008 Poster Presentations Thyroid (146 abstracts)

First rapid and automated immunoassay for TSH receptor antibodies

Dieter Gassner 1 , Ruth Golla 1 , Werner Stock 1 , Jane Sanders 2 & Bernard Rees Smith 2


1Roche Diagnostics GmbH, Penzberg, Germany; 2RSR Ltd, Cardiff, UK.


Hyperthyroidism in Graves’ disease is due to TSH receptor (TSHR) autoantibodies (TRAb) directed against the TSH binding pocket. Detection of TRAb in clinical rou-tine is performed by 2nd gen assays using human or porcine TSHR. Such TSH bin- ding inhibition immunoglobulin (TBII) assays determine the ability of TRAb to inhi- bit the binding of labelled TSH to immobilized TSHR. TRAb are present in low con- centrations and mostly recognize conformational epitopes. The conformational structure of the TSHR is sensitive to thermal stress. Incubation times of current as- says must be for a minimum of 2 h to obtain good sensitivity. Due to these tech- nical difficulties no rapid automated TRAb assay could be developed so far.

We report on the 1st automated TRAb assay on the Elecsys/ cobas e immuno- assay platform. TRAb inhibit the binding of a human monoclonal thyroid stimula- ting autoantibody (M22; labelled with a ruthenium complex) to preformed immuno- complexes based on aggregates of solubilised multiple porcine TSHR (pTSHR) and a mouse monoclonal capture antibody (4E31 IgG; labelled with biotin). 4E31 does not interfere with the binding of TRAb and M22 to the pTSHR. The lyophili- zed immunocomplexes are stabilized after reconstitution by chemical chaperones. The assay uses a delayed competitive test principle. Total assay time is 3×9 min only. Firstly, sample TRAb – if present – bind to the multiple TSHR binding sites. Secondly, TRAb are allowed to interact with the TSHR further. Thirdly, labelled M22 and streptavidin-coated microparticles are added. M22 binds to still free bin- ding sites. Immunocomplexes are bound to the solid phase via interaction of biotin and streptavidin. Assay calibration is against the NIBSC 90/672. Its measuring range extends from 0.3–40 IU/l. The functional sensitivity is ~0.9 IU/l.

The automated Elecsys Anti-TSHR correlates well with current TBII assays and provides clinical performance and total precision which will meet customer needs.

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