Graves' Disease is an autoimmune disease in which the thyroid over produces thyroid hormones. The receptor for TSH (thyroid-stimulating hormone from the pituitary) is the primary target of the immune system in Graves' disease. The receptor-stimulating antibodies bind to the receptor, stimulating it like TSH does. Thus, like TSH, they stimulate an increased production of thyroid hormones, or hyperthyroidism.