Distribution of cytokeratin markers in Barrett's specialized columnar epithelium

Background & Aims: The cell of origin for Barrett's epithelium is unknown. A multilayered epithelium within Barrett's epithelium has been noted recently. To investigate the hypothesis that this multilayered epithelium may be a transitional stage between squamous and Barrett's epithelium, cytokeratin immunocytochemistry was used to examine normal squamous, Barrett's, and multilayered epithelium. Methods: Seventeen endoscopic biopsy specimens taken from the squamo-Barrett's junction of 8 patients with Barrett's epithelium and 3 biopsy specimens from the gastroesophageal junction of 3 patients without Barrett's epithelium were investigated. Antibodies to cytokeratins 4 and 13 were used as markers for squamous differentiation, and antibodies to cytokeratins 8 and 19 were used as markers for glandular differentiation. Coded samples were evaluated by immunocytochemistry. Results: In patients with Barrett's epithelium and control patients, staining with columnar markers was confined to either the Barrett's or the gastric columnar epithelium. Staining with squamous markers was confined to the adjacent squamous epithelium. In contrast, focal areas of multilayered epithelium amidst Barrett's epithelium stained with cytokeratin antibodies for both squamous and columnar epithelium. Conclusions: A focal multilayered epithelium within Barrett's epithelium that expresses concurrently both squamous and glandular cytokeratin markers is described. These findings suggest a multipotential cell as the cell of origin of Barrett's epithelium.