Accumulation of radioactively labeled antithyroglobulin antibody by thyroid carcinoma

The present experiments were undertaken to investigate (1) accumulation of radioactively labeled anti-thyroglobulin antibody by thyroid carcinomas and (2) the mechanism by which radioactively labeled antibody reaches to and stays in carcinoma cells. Anti-thyroglobulin antibody was purified by affinity chromatography using serum obtained from a patient with Hashimoto's disease. 125I-labeled anti-thyroglobulin antibody was injected into nude mice bearing transplanted human thyroid carcinomas. Scintigrams were taken 3 and 7 days after injection. Mice were killed thereafter and the radioactivity in each tissue and in serum was analyzed by gel filtration and affinity column chromatography of thyroglobulin, anti-thyroglobulin antibody and anti-human IgG antibody. In a total thyroidectomized patient with a metastatic thyroid carcinoma of the lymph node, 131I-labeled antibody was injected and scintigraphy and blood sampling performed for 7 days after injection. Scintigrams of the mice clearly showed the highest density over the transplanted carcinoma. Most radioactivity in the carcinoma was found to be in the thyroglobulin-antibody immune complex, while in other tissues, including serum samples, the radioactively was in free anti-thyroglobulin antibody. Scintigrams of the patient also showed a hot area over a metastatic carcinoma of the lymph node. It is concluded that (1) radioactively labeled anti-thyroglobulin antibody is accumulated by thyroid carcinoma in spite of the presence of thyroglobulin in blood and stays in cells as thyroglobulin-antibody immune complex, and (2) radioimmunodetection of thyroid carcinomas using labeled anti-thyroglobulin antibody is useful especially for patients with metastases which produces thyroglobulin and do not take up radioiodide.