Variable neutralization by purified TSHR A subunits of TSHR autoantibodies from hypothyroid patients with TBAb’s. Flow cytometry was performed using sera from seven patients. Sera were preincubated in either buffer alone or in buffer containing TSHR-289 (0.1 μg/0.1 ml of serum diluted 1:50) before addition to CHO cells expressing the wild-type (TSHR-10,000 cells) or the GPI-anchored TSHR ectodomain (ECD-GPI cells). Net fluorescence values for the sera are indicated after subtraction of background fluorescence obtained with untransfected CHO cells. Note the difference scales for the Yaxes here and in Figure 6, reflecting the higher titers of TBAb versus TSAb.