In vitro synthesized TSH receptor as a tool for autoantibody detection.

Immunoprecipitation is a reliable method for the detection of many antigens but so far this has not been applied to the TSH receptor. We demonstrate here a novel assay for the detection of antibodies to the TSH receptor using in vitro synthesized protein. The TSH receptor was translated in vitro as a stable protein of 87 kD (full length) and 50 kD (extracellular), respectively. The 50 kD protein reacted by immunoprecipitation analysis with murine and human monoclonal antibodies, polyclonal rabbit sera and with a proportion of unfractionated Graves' disease sera. A limited form of epitope mapping was achieved with the murine monoclonal antibodies. This assay may serve as a new method for the detection of autoantibodies to the TSH receptor from patients' sera.