METHOD TO DIFFERENTIATE BETWEEN THYROGLOBULIN DERIVED FROM NORMAL THYROID-TISSUE AND FROM THYROID-CARCINOMA BASED ON ANALYSIS OF REACTIVITYTO LECTINS

Objective.-The composition of sugar chains on thyroglobulin (Tg) produ ced in thyroid carcinoma cells (C-Tg) is different from Tg produced in normal thyroid tissues (N-Tg). In this study, we designed a new metho d for detecting Tg derived from thyroid carcinoma based on the differe nces between C-Tg and N-Tg in the reactivity with lectins, Materials a nd Methods.-Thyroglobulin preparations obtained from various thyroid t issues were incubated with lectins, and the amount of lectin-unbound T g (ub-Tg) in the supernatant relative to Tg untreated with: lectin was determined by enzyme-linked immunosorbent assay and expressed as ub-T g(%). In addition, to study further the differences in glycosylation b etween C-Tg and N-Tg, concanavalin A binding to Tg digested with Staph ylococcus aureus V8 protease was analyzed on nitrocellulose membrane a fter Western blotting. Results.-The ub-Tg(%) in C-Tg from papillary ca rcinoma was significantly higher than in Tg from Graves' disease, beni gn goiter, and normal thyroid tissue for both concanavalin A and ricin us communis agglutinin-120. Concanavalin A did not appear to bind to T g from papillary carcinoma after V8 treatment by Western blot analysis . The ub-Tg(%) in Tg from follicular adenoma was significantly higher than C-Tg from follicular carcinoma, whereas there were no differences in ub-Tg(%) between follicular carcinoma and normal thyroid tissue in concanavalin A treatment. Conclusions.-These results suggest our new methods can distinguish both between C-Tg from papillary carcinoma and N-Tg, and between follicular carcinoma and follicular adenoma in thyr oid tissue specimens. Thus, this type of analysis may be applicable to differentiate C-Tg from N-Tg in thyroid aspirates for the adjunctive cytodiagnosis of thyroid carcinoma.