COMPARATIVE STUDIES OF THYROGLOBULINS IN FUNCTIONING AND NON-FUNCTIONING THYROID TUMORS

Abstract

The chemical and immunological properties of thyroglobulins (Tg) in the tissue obtained from patients with two types of thyroid tumors, i.e., functioning and non-functioning, were compared with the properties of Tg which was isolated from the peripheral tissue adjacent to the individual tumor.The amount of Tg per unit weight of tissue was much smaller in malignant tumors (carcinoma) of the thyroid than in normal thyroid tissue or benign tumors (adenoma). Moreover, the Tg content of the peripheral tissue adjacent to thyroid carcinoma was also decreased slightly, in contrast to the histological examination which showed normal features.In the non-functioning tumors, especially in carcinoma, Tg contained less iodine and thyroid hormone. However, the iodine content of the peripheral tissue remained at about the level of that of normal Tg. In contrast to these findings, Tg in the functioning tumor was iodinated at a level close to that of normal tissue, and, interestingly, Tg from the peripheral tissue usually had a lower iodine content than the tumor Tg.In the carbohydrate moiety, the sialic acid content of Tg was decreased in both functioning and non-functioning tumors. Furthermore, there was no relationship between the amount of sialic acid and that of iodine, as observed with Tg in normal thyroid tissue. The lower sialic acid content was in accordance with the different chromatographic properties of normal Tg in lectin-gel, which depended on the unusual structure of the oligosaccharide chains seen in tumor Tg.In the immunological properties, Tg of non-functioning tumors, both adenoma and carcinoma, generally showed a lower affinity for antiserum against Tg than did normal Tg. Furthermore, even Tg from normal peripheral tissue adjacent to carcinoma had decreased affinity for antibodies. On the other hand, Tg of functioning tumors and their adjacent tissues had higher affinity for the antiserum than normal Tg, in some cases. These findings suggest that various Tg preparations from tumor and adjacent tissue are heterogeneous with respect to their conformation, and therefore differ from normal tissues, and that the differences have no relationship to the iodine content.