Expression of cytokeratins in early neoplastic epithelial lesions of the uterine cervix.

Polyclonal and monoclonal antibodies to cytokeratin polypeptides were used to study the expression of these intermediate filament proteins in normal, squamous metaplastic, and neoplastic epithelium of the uterine cervix, in order to investigate the morphogenesis of early epithelial changes preceding cervical squamous cell carcinoma. A polyclonal keratin antiserum showed a positive reaction in all different epithelial cell types of the uterine cervix. A positive reaction was also found in subcolumnar reserve cell hyperplasia, in squamous metaplastic and dysplastic cells, and in (squamous) carcinoma in situ. A monoclonal antibody specific for columnar epithelium (RGE 53) gave a positive reaction in endocervical columnar cells and in some immature metaplastic cells but was negative in subcolumnar reserve cells, squamous (metaplastic) cells, dysplastic cells, and most cases of carcinoma in situ. Another monoclonal cytokeratin antibody (RKSE 60) pointed to early keratinization in light microscopically nonkeratinizing squamous (metaplastic) and dysplastic epithelium. A possible overlap in staining patterns of RGE 53 and RKSE 60 was seen in some cases of immature metaplasia. Morphologic changes occurring in the transformation zone upon dedifferentiation are accompanied by alterations in cytokeratin expression. Similarities in cytokeratin expression were found between dysplasia and carcinoma in situ on one hand and subcolumnar reserve cell hyperplasia and squamous metaplasia on the other. This study favors an epithelial origin and a squamoid nature of subcolumnar reserve cells.