Characterization of Apparently Paradoxical Thyrotropin Binding Inhibitory Immunoglobulins With Neutral Bioactivity.

We present here the TBIIs with neutral bioactivities found in the patient with autoimmune thyroid disease, which strongly inhibit TSH binding to the TSH-R but exerts neither TSAb nor TSBAb activity. Differences in the methods of detecting TRAb between TBII in vitro and bioassay may cause the discrepancy. Although serum sample S may be an extreme example, a variety of TRAb that not only stimulates or blocks but also interferes with TSH-R binding for only a short time may exist in the serum samples of GD patients.