Monoclonal antibodies to thyroglobulin elucidate differences in protein structure of thyroglobulin in healthy individuals and those with papillary adenocarcinoma.

Monoclonal antibodies specific for human thyroglobulin (Tg) from normal subjects were prepared by the hybridoma technique. Antibodies from three clones (clones B2F, C6E, and C6G) were found to produce linear Scatchard plots, as predicted for homogeneous antibodies. Based on different patterns of cross-reactivity with Tg from various species, these monoclonal antibodies recognized different determinants on the Tg molecule. Moreover, antibodies from clone B2F bound simultaneously with clone C6E or C6G to Tg. Therefore, antibody from clone B2F must bind to a site on Tg distant from those recognized by clone C6E or C6G. The monoclonal antibodies C6G and C6E bound almost equally to normal Tg and Tg from patients with Graves' disease, adenoma, follicular carcinoma, and papillary adenocarcinoma. In contrast, whereas clone B2F bound equally well to normal Tg and Tg from patients with Graves' disease, adenoma, and follicular carcinoma, this clone bound poorly to Tg from patients with papillary adenocarcinoma. Since the binding activity of clone B2F for unfolded or degenerated Tg was remarkably decreased, these differences in binding activities to native Tg may reflect changes in conformation of the Tg molecule. Thus, the results indicate there may be conformational changes in Tg from patients with different thyroid diseases.