The content and chemical and immunological properties of
thyroglobulin (Tg) and the activity of
thyroid peroxidase (TPO) were studied in nodular and extranodular (periphery) thyroid tissue from patients with functioning thyroid
tumors (hot nodules). From the present observations, the
tumor extracts contained fairly large amounts of Tg, similar to that in the periphery tissue, while the content of Tg was markedly decreased in non-functioning thyroid
tumors (cold nodules). The
iodine content of Tg was significantly higher in nodular tissue compared with periphery tissue. These observations were in contrast to the results seen in the cold nodules in which
hormone synthesis was defective. On the nature of
carbohydrate moiety as compared with normal tissue,
oligosaccharides of Tg from the periphery tissues changed in a manner similar to that of
tumor oligosaccharides. That is, high-
mannose type
oligosaccharides were markedly decreased whereas multiantennary and unidentified
oligosaccharides were increased. These observations were similar to those of non-functioning
tumors. The content of
sialic acid decreased markedly both in the
tumor and periphery tissues. Immunologically, Tg preparations of the
tumor and periphery tissue did not show the same affinity to the
antibodies, depending on the content of
iodine. Therefore, it seems that the contribution of the
iodine content and iodo-
amino acid has little or no significance in the heterogeneous nature of Tg-immunogenecity. Benign
tumors and the periphery tissue were subjected to assay for
thyroid peroxidase activity by the method employing
guaiacol as the second substrate. The specific activities of the
tumors were generally higher than those of periphery tissues, both in functioning and non-functioning benign
tumors. In non-functioning
carcinoma, on the other hand, TPO activities were lower in
tumor portions than in periphery portions. This indicates that non-functioning
thyroid carcinomas have a different characteristic.