The detection of a unique antigen associated with papillary thyroid carcinoma

We produced antibodies against a thyroid papillary carcinoma homogenate (PCAb) and analyzed antigens recognized by this antibody using western blotting. Fifty-four thyroid tissue specimens and 6 control tissue specimens obtained from non-thyroid carcinoma (gastric tissue, colon and liver) were analyzed. Consequently, an antigen of 40 kDa in size was found in 16 of 16 (100%) of papillary thyroid carcinoma from primary lesions and in 2 of 2 (100%) papillary thyroid carcinoma from metastatic foci, whereas it was not detected in thyroid tissue samples from follicular carcinoma, anaplastic carcinoma, follicular adenoma, adenomatous goiter, Graves' disease and normal thyroid tissues. The reactivity of thyroglobulin antiserum (TgAb) to this 40 kDa antigen was tested by western blotting and showed that TgAb did not appear to recognize the 40 kDa antigen. Moreover PCAb, after treatment with Tg, still reacted with this 40 kDa antigen. Therefore, this 40 kDa antigen might be different from Tg. Furthermore, to inspect the structure of this antigen, the effect of some chemicals and enzymes such as 2-mercaptoethanol, sodium dodecyl sulfate, ethanol and protease on the reactivity of PCAb to the 40 kDa antigen were analyzed. The results of these experiments suggested that this 40 kDa antigen may have a peptide structure. To our knowledge, the finding reported here represents the first demonstration of the protein specifically present in papillary thyroid carcinoma. Further investigations should elucidate the characteristics of this antigen and may contribute to definitive diagnosis of thyroid carcinoma as well as improving the understanding of the mechanisms involved in developing the thyroid carcinoma.