Reverse transcriptase is elevated in the thyroid tissue from Graves' disease patients

OBJECTIVE Hypertrophy of the thyroid gland in Graves' disease is related to an autoimmune response directed against TSH receptors found in thyroid cel ls. Recently, investigators have suggested that autoimmune diseases, includ ing thyroid diseases may, at least in part, correlate with the expression o f proteins encoded by the retroviral genome. In the present study, to confi rm the correlation between thyroid autoimmune disorders and retroviral infe ctions, we examined reverse transcriptase (RT) activity in thyroid tissues as a marker of retroviral infection. PATIENTS AND MEASUREMENTS Thyroid tissues obtained at surgery from patients with various thyroid disorders (normal thyroid adjacent to adenoma, six ca ses; Graves' disease thyroid tissue, 25 cases; adenoma, eight cases; papill ary carcinoma, 12 cases; Graves' disease peripheral blood lymphocytes, 11 c ases) were used for RT assay, using a specific, improved assay system. RESULTS Thyroid tissue extracts from patients with Graves' disease containe d high RT activity which resembled that demonstrated in retroviruses. The R T existed in the thyroid tissue as a complex, with endogenous template RNA, and the activity was confirmed not to be due to other DNA polymerases. CONCLUSION Retroviral RT distinguished from known cellular DNA polymerases is expressed in the thyroids of patients with Graves' disease, In a permiss ive genetice and immunological environment, retroviral DNA integrated into genomic DNA could precipitate the onset of Graves' disease.