CYTOKERATIN EXPRESSION IN NORMAL HUMAN BULBAR CONJUNCTIVA OBTAINED BYIMPRESSION CYTOLOGY

Purpose. To document the cytokeratin expression patterns in the normal human conjunctival epithelium obtained directly from patients using i mpression cytology. Methods. Impression cytology specimens were obtain ed from normal volunteers using pure nitrocellulose membranes rather t han cellulose acetate. The 31 volunteers of bath sexes ranged in age f rom 18 to 79 years. Impression cytology specimens were analyzed for in dividual cytokeratins by either immunocytochemistry or electrophoresis with immunoblotting using a defined panel of monoclonal antibodies. R esults. Using the corroborative methods of immunocytochemistry and ele ctrophoresis with immunoblotting, cytokeratins characteristic of nonke ratinized, stratified (K4 and K13),simple (K8 and K19), and glandular epithelia (K7) were present in the superficial layer(s) of normal huma n conjunctiva. Cytokeratins typical of keratinized epithelia (K1, K2, and K10) and the keratinization-related proteins filaggrin and involuc rin were not expressed in normal conjunctival epithelium. Conclusions. The normal human conjunctiva demonstrates a unique cytokeratin expres sion pattern containing cytokeratins characteristic of nonkeratinized, stratified epithelia, as well as others more typical of a simple diff erentiation pattern, a glandular differentiation pattern, or both. The se findings provide a foundation for examining changes in the cytokera tin expression pattern in diseased human conjunctival epithelium using impression cytology.