ABERRANTLY EXPRESSED CYTOKERATIN-1, A TUMOR-ASSOCIATED AUTOANTIGEN INPAPILLARY THYROID-CARCINOMA

Papillary thyroid carcinoma (PTC) is a somewhat puzzling disease, comb ining a propensity to metastasize with an indolent clinical course. Th e often pronounced T cell-dominated inflammatory infiltrate seen in PT C tumors has prompted us to search for signs of a tumor-induced immune response. In previous studies, we have demonstrated large tumor-speci fic deposits of IgG and complement in PTC tissue and isolated a putati ve target antigen. This investigation examines the presence of autoant ibodies to cytokeratin I, a high m.w. cytokeratin normally expressed o nly in suprabasal keratinocytes, in the serum and tumor tissue of PTC patients. Using immunoprecipitation and Western blot, cytokeratin 1-re active autoantibodies were demonstrated in 80% of the PTC sera tested, and tumor-derived antibodies were shown to precipitate cytokeratin 1. Using immunohistochemistry, cytokeratins 1 and 10 were found in a lar ge proportion of PTC tumors (39/44) but were absent from normal thyroc ytes of most PTC-bearing glands. Our results indicate that this protei n is expressed aberrantly in neoplastic cells and is immunogenic in th is context. (C) 1997 Wiley-Liss, Inc.