Freddo, “Cytokeratin expression in normal human bulbar conjunctiva obtained by impression cytology

Purpose. To document the cytokeratin expression patterns in the normal human conjunctival epithelium obtained directly from patients using impression cytology. Methods. Impression cytology specimens were obtained from normal volunteers using pure nitrocellulose membranes rather than cellulose acetate. The 31 volunteers of both sexes ranged in age from 18 to 79 years. Impression cytology specimens were analyzed for individual cytokeratins by either immunocytochemistry or electrophoresis with immunoblotting using a defined panel of monoclonal antibodies. Results. Using the corroborative mediods of immunocytochemistry and electrophoresis with immunoblotting, cytokeratins characteristic of nonkeratinized, stratified (K4 and K13), simple (K8 and K19), and glandular epidielia (K7) were present in the superficial layer(s) of normal human conjunctiva. Cytokeratins typical of keratinized epithelia (Kl, K2, and K10) and the keratinization-related proteins filaggrin and involucrin were not expressed in normal conjunctival epithelium. Conclusions. The normal human conjunctiva demonstrates a unique cytokeratin expression pattern containing cytokeratins characteristic of nonkeratinized, stratified epithelia, as well as others more typical of a simple differentiation pattern, a glandular differentiation pattern, or both. These findings provide a foundation for examining changes in the cytokeratin expression pattern in diseased human conjunctival epithelium using impression cytology