Immunolocalisation of E-cadherin and -catenin in human pterygium

Aim: The pterygium represents an invasion of a wing of altered ocular surface tissue into the normal cornea. The head itself is slightly elevated and white, which is the only site of firm adhesion to the globe. The mechanisms of cell proliferation and adhesion in pterygium epithelium, however, are unknown. The aim of this study was to analyse the expression of cell adhesion molecules in pterygium tissues. Methods: Six pterygia were surgically removed using the bare-sclera procedure, and two normal corneas and a normal bulbar conjunctiva were also obtained. Formalin-fixed, paraffin-embedded tissues were analysed by immunohistochemistry with anti-E-cadherin and β-catenin antibodies. Results: Immunoreactivity for E-cadherin was not detected in the normal cornea and conjunctiva. In contrast, all corneal and conjunctival epithelial cells showed a weak homogeneous immunoreaction for β-catenin on the cell membrane. In the pterygium head, the thickness was relatively marked compared with the body, and normal conjunctival and corneal epithelia. E-cadherin as well as β-catenin was heterogeneously expressed in the cell membrane and cytoplasm of a variety of epithelial cells, whereas the expression was less marked in the body. Several epithelial cells showed intense nuclear immunoreactivity for β-catenin. Immunoreactivity of β-catenin, but not E-cadherin, was detected in only a few stromal cells, which were less marked than in epithelial cells. Conclusion: It is suggested that E-cadherin and β-catenin are concentrated in pterygium tissue, and are possibly involved with epithelial proliferation and adhesion.