Cytokeratin 13 is a new biomarker for the diagnosis of limbal stem cell deficiency

PURPOSE The purpose of this study was to evaluate the expression of cytokeratin (K) 13 on the corneal surface and to validate its application in the diagnosis of limbal stem cell deficiency (LSCD). METHODS This prospective comparative study included 26 corneal impression cytology (IC) specimens from patients diagnosed with LSCD. Twenty-three IC specimens from normal donors served as controls. K12 and K13 expression were detected on the IC specimens by immunohistochemistry study. The number of K12+ or K13+ cells in all areas of the IC was quantified using ImageJ software. RESULTS The epithelial cells harvested from IC specimens from control corneas were all K12+. In eyes with LSCD, K13+ and K12+/K13+ cells accounted for 93.8% and 2.6%, respectively, in the cornea. In eyes with sectoral LSCD, the median number of K13+ cells in the clinically affected area was higher than that in the unaffected area (810.0 vs. 115.0 cells/mm2; P < 0.001). No significant correlation was found between the LSCD severity and the number of K12+ cells (r = -0.284, P = 0.16) or K13+ cells (r = -0.011, P = 0.95). The presence of at least 16 K13+ cells/mm2 was suggestive of LSCD. CONCLUSIONS Identification of K13+ cells on IC specimens provides a simple and reliable method to detect conjunctival epithelial cells on the cornea. K13 is a marker for diagnosing LSCD and localizing the involved area in sectoral LSCD.