Anti-TSH receptor antibodies are IgG immunoglobulins which, by binding to the thyrotropin receptor (Thyroid-stimulating hormone receptor TSHR), cause its stimulation or inhibition. The link created between TRAb
Anti-TSH receptor antibodies are IgG immunoglobulins which, by binding to the thyrotropin receptor (Thyroid-stimulating hormone receptor TSHR), cause its stimulation or inhibition. The link created between TRAb and the TSH receptor prevents endogenous TSH from carrying out its physiological function. The dosage of anti-TSH receptor antibodies, with highly sensitive methods, assumes importance for the diagnosis of Graves' disease. The TRAb family can be divided into two categories: TRAb which by binding to TSHR mimic the biological action of TSH, or the production of thyroid hormones. These autoantibodies are present in most patients (TSAb). TRAb which by binding to TSHR block it, the resulting result is the absence of thyroid hormone production (TBAb). The reason why the TSH receptor behaves in two ways, stimulating or inhibiting the production of T3 and T4, is due to its particular structure.
The receptor is a 764 AA polypeptide, consisting of three portions such as extracellular, transmembrane and intracellular. In the extracellular portion there is the binding site of TSH and therefore of TRAb (TSAb and TBAb). The regions that are recognized as epitopes by TRAb appear to be very close, so much so that some amino acids appear to be shared. This discovery was possible thanks to the isolation of the human monoclonal autoantibody and its expansion on an animal model: mouse and rat. Several monoclonal antibodies (MAbs) have been isolated, including the most important: the stimulating Mabs M22 and the inhibiting Mabs 5C9.
