Production of Ab2β, Anti-idiotypic Monoclonal Antibodies, Specific for Human Thyrotropin Receptor

We had previously selected five monoclonal antibodies (mAb1) upon their specific binding to human thyrotropin (hTSH). These mAbs1, which are specific for two distinct epitopes of the hTSH β-chain, also inhibit the hTSH binding to human thyroid membrane preparations. We then immunized BALB/c mice with the various mAbs1 in attempt to generate anti-idiotypic Abs (Ab2) directed to the hTSH receptor (hTSHR). Five hybridomas secreting monoclonal antibodies (mAb2) to the hTSHR were selected from one mouse immunized with the mixture of the five mAbs1. These monoclonal antibodies to the hTSHR were selected upon their ability to specifically bind to the hTSHR. Moreover, we showed that binding of mAbs2 to the individual mAbs1 used for immunization was specifically inhibited by hTSH and not by insulin or by human chorionic gonadotrophin, a highly related glycoprotein hormone. The five mAbs2 inhibited the binding of iodine-labeled hTSH to its receptor by 8 to 41%: moreover, two of them stimulated the adenylatecyclase system of the thyroid cells. With respect to their properties, mAbs2 were classified as mAb2-β.