Expression of the receptor tyrosine kinases, epidermal growth factor receptor, ErbB2, and ErbB3, in human ocular surface epithelia

Purpose. To investigate the distribution and relative level of expression o f the receptor tyrosine kinases, epidermal growth factor receptor (EGFR), E rbB2 and ErbB3, in human ocular surface epithelia. Methods. Immunofluoresce nt staining was performed to identify expression of the EGFR, ErbB2 and Erb B3 in the corneal, limbal and conjunctival epithelium in tissue sections an d impression cytologies taken from normal human eyes. Western blotting was undertaken to confirm the results of immunofluorescent staining. Results. T he three receptor tyrosine kinases, EGFR, ErbB2 and ErbB3, were detected in human corneal, limbal and conjunctival epithelia by immunofluorescent stai ning. Strong staining for the EGFR was observed in the basal epithelial cel ls at all 3 sites and throughout the corneal epithelium. Minimal or no stai ning for the EGFR was observed in the superficial conjunctival and limbal e pithelia. The strongest staining for ErbB2 and ErbB3 was observed in the su perficial ocular surface epithelium. All three receptors were detected in t he corneal, limbal and conjunctival epithelium by western blot. Conclusion. EGFR, ErbB2 and ErbB3 are expressed by the ocular surface epithelia. EGFR is preferentially expressed by the basal epithelial cells that have the gre atest proliferative potential. In contrast, ErbB2 and ErbB3 are preferentia lly expressed by the superficial differentiated ocular surface epithelia.