[Immunohistochemical investigation on expression of cytokeratins in normal epithelium, precancerous lesions and carcinomas of the hypopharynx].

In order to obtain a more objective method to evaluate epithelial disorders and carcinomas of the hypopharynx, the expression pattern of cytokeratins (CKs) was investigated by ABC technique using several kinds of monoclonal antibodies that react monospecifically with each subclass of CKs. In normal epithelia, CK-19 was strongly positive in the basal layer but apparently reduced in suprabasal layers and completely negative in superficial layers, while CK-13 showed a striking contrast to CK-19, being expressed within the whole thickness of epithelia except only in the basal layer. These 2 subclasses were also observed in "abnormal" epithelia, and characteristic changes of their combination were demonstrated in proportion to the histological gradings. In invasive carcinomas, CK-19 was strongly positive in all carcinoma cells of poorly differentiated carcinomas. It was sporadically positive in moderately differentiated carcinomas, the more differentiated the more sporadic. It was completely negative in well differentiated carcinomas. CK-13, on the other hand, was negative in poorly differentiated carcinomas but positive in keratinized cells of moderately or well differentiated carcinomas. Strong expression of CK-1 was observed only in well keratinized cells of hyperkeratotic epithelia and well differentiated carcinomas. These characteristic findings are consistently observed in all samples and, then, may be useful in evaluating epithelial disorders and carcinomas of the hypopharynx, when used in conjunction with standard histological techniques. It seems most likely that these results play a part in investigating normal and abnormal processes of cell differentiation.