Graves' disease: xenotransplantation model (athymic nude mice).

The immunological mechanisms leading to Graves' disease are not yet fully understood. The athymic nude mouse has immunological properties which allow in vivo studies concerning autoimmune thyroid diseases with special regard to the interaction of TSH, TSH receptor antibodies, cytokines, antithyroid drugs, TSH receptor antagonists and human lymphocytes. In our own studies thyroid tissues of patients with Graves' disease, toxic adenomas and non-toxic nodular goiter were xenotransplanted to athymic nude mice. Histology, morphology and function of the transplants were examined 2 days to 2 weeks after injection of bovine TSH, interferon-gamma, Graves' sera with or without addition of a TSH-receptor antagonist and lymphocytes of patients with Graves' disease. Thyroid transplants can be stimulated by TSH, interferon-gamma, Graves' sera and immunoglobulin G. Additional treatment with asialoagalacto-hCG inhibits stimulation of the immunoglobulin. Furthermore, preliminary results show, that engrafted peripheral and especially intrathyroidal lymphocytes from patients with Graves' disease specifically migrate into human thyroid transplants ("homing") and are able to induce functional and histological changes in these tissues. In summary, the xenotransplantation model is well suited for studies concerning pathogenesis, diagnosis and therapy of autoimmune thyroid diseases.