title: Expression of major histocompatibility complex class I antigens in normal and transformed rat thyroid epithelial cell lines.
abstract: Recent evidence suggests that the expression of abnormally high amounts of major histocompatibility complex (MHC) class I molecules may be a feature of at least some kinds of transformed cells. To investigate this aspect of neoplastic transformation we studied the expression of MHC class I antigens in an experimental model of normal, tumor-derived, and virus-transformed thyroid epithelial cell lines. The expression of MHC class I antigens has been studied by means of several monoclonal antibodies directed against either monomorphic or polymorphic epitopes and quantified by flow cytometry. Class I specific mRNA transcripts have been also analyzed by Northern blot hybridization, using a mouse genomic H-2 DNA probe. Our results indicate a modulation of MHC class I expression associated with loss of the differentiated phenotype and with transformation of thyroid epithelial cell lines. Undifferentiated cells in fact show a small quantity of these antigens, because acquisition of a fully differentiated phenotype is associated with an increase in their expression. Cell lines derived from thyroid tumors show reduced expression of MHC class I antigens, as compared to differentiated cells. Conversely, cells transformed in vitro by a retrovirus carrying the v-raski oncogene exhibit an increase in these antigens in comparison to their normal differentiated counterparts. Cells infected with a mutant virus able to transform cells only at the permissive temperature of 33 degrees C show a similar increased expression. After a shift to the nonpermissive temperature of 39 degrees C, infected cells, even those losing the transformed phenotype retain the same increased amount of MHC class I antigens. Our data suggest that the modulation of MHC class I antigen expression is strongly associated with transformation in thyroid epithelial cells.
mesh_terms: D000230:Adenocarcinoma / Q000276:immunology* / Q000473:pathology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000912:Antibodies, Neoplasm / Q000276:immunology; D000951:Antigens, Neoplasm / Q000096:biosynthesis*; D002277:Carcinoma / Q000276:immunology* / Q000473:pathology; D002454:Cell Differentiation; D002460:Cell Line; D002472:Cell Transformation, Viral; D004848:Epithelium / Q000276:immunology / Q000473:pathology; D005786:Gene Expression Regulation; D006649:Histocompatibility Antigens / Q000096:biosynthesis*; D007708:Kirsten murine sarcoma virus; D051381:Rats; D011916:Rats, Inbred F344; D013961:Thyroid Gland / Q000166:cytology / Q000276:immunology*; D013964:Thyroid Neoplasms / Q000276:immunology* / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D000912:Antibodies, Neoplasm; D000951:Antigens, Neoplasm; D006649:Histocompatibility Antigens; C038353:histocompatibility antigens RT, rat