Intermediate-sized filaments in cells of normal human colon mucosa, adenomas and carcinomas.

The distribution of intermediate - sized filaments in human colon mucosa as well as in adenomas and carcinomas of the colon was studied by means of both immunohistology and electron microscopy. The epithelial cells of the colonic mucosa are definitely labelled with antibodies against prekeratin (cytokeratin). Interwoven filaments of the prekeratin type are present in the basal compartments of the epithelial cells; they surround the nuclei and mucus droplets and form an apical skeletal disc. Pericryptal connective tissue is prekeratin negative and vimentin positive. Benign hyperplastic polyps have a high content of prekeratin. The potential precursors of colonic carcinoma, i.e., the tubular and villous adenomas, also show an increase in intermediate-sized filaments of the prekeratin type. Correspondingly, electron microscopy reveals elongated bundles of intermediate-sized filaments arising from the desmosomes of the lateral and basal cell membranes. The prekeratin content is particularly high in adenocarcinomas and highest in mucinous carcinomas. As expected, the stroma of all neoplasms studied is prekeratin-negative, but distinctly vimentin-positive. In one moderately differentiated adenocarcinoma there was evidence of "vimentin-positive" tumor cells. These changes may be caused by binding of cytokeratins with an unknown substance in vimentin antisera, as observed similarly by Moll et al. (1982) in a transitional cloacogenic carcinoma.