Table 2 Two main types of thyroid antibody assays
Competitive Binding Assays | Cell-Binding Assays (bioassays) | |
|---|---|---|
Principle | Measure the ability of TRAbs to inhibit TSH receptor ligand binding | Measure the effect of TRAbs on cAMP levels in effector cells, differentiating TSI, TBA, or neutral antibodies |
What is measured | Concentration of TSH binding inhibiting immunoglobulins (TBIIs) in the patient serum | Concentrations of cAMP levels in the effector cells |
Ligand Used | 1st and 2nd generation: Bovine TSH with porcine/ human TSH receptor; 3rd generation: Biotin-labelled M22 human monoclonal thyroid stimulating antibody with porcine TSH receptor-coated ELISA plates | 1st and 2nd generation: Human or porcine thyroid cells; later assays: Chinese hamster cells transfected with human TSH receptor |