[Cytokeratins and transitional epithelium of the bladder. Particular distribution of cytokeratins]

Abstract

The purpose of this study was to determine the tissue distribution of certain cytokeratins in the urothelium. A series of ten cystectomy specimens containing normal tissues was investigated by immunocytochemical labeling with specific antibodies against cytokeratins 19, 18, 8, 7, 10. Monoclonal antibodies were used on frozen sections. Distribution of keratin was correlated with morphologic changes. All specimens were lined by a normal transitional epithelium. Low molecular weight cytokeratins (polypeptides 19, 18, 8, 7) were detected in all cell layers. Anticytokeratin 19 stained epithelium in a rather uniform way. Different antibodies specific for cytokeratin 18 reacted differently on the same tissue. With certain anticytokeratins 18 and 8, a higher staining intensity was found in superficial layers as compared with intermediate cell layers. So-called "umbrella" cells were strongly stained. Anticytokeratin 10 revealed very rare endocrine-like cells. This normal urothelial pattern is in agreement with previous reports. This pattern of expression of cytokeratin polypeptides differs from that of nonkeratinizing squamous epithelium. Therefore, histological differentiation of epithelia is accompanied by pronounced changes in the expression of cytokeratin polypeptides.