Fig. 17.11 shows the mechanism of interaction of TSH with TSH-R(s) antibodies. The target autoantigen in patients with Graves' ophthalmopathy remains controversial. The gene for a 64-kDa membrane protein of the eye muscle has recently been cloned. IgG antibodies to this antigen are found in many normal human sera, although increased concentrations are detected in the sera of Graves' ophthalmopathy patients. The anti-64kDa antibodies may merely represent natural autoantibodies that react with recurrent autoepitopes.
