DISTRIBUTION OF ANTIOXIDANT ENZYMES IN THE NORMAL AGED HUMAN CONJUCTIVA - AN IMMUNOCYTOCHEMICAL STUDY

Abstracl Background: The purpose of the study was to map the precise l ocation of four antioxidant enzymes in the normal human conjunctiva. M ethods: Conjunctival tissue (seventeen specimens) from seven patients was processed for light microscopy and immunogold electron microscopy. Antibodies were used to label glutathione peroxidase, glutathione S-t ransferase (acidic and neutral forms) and copper/zinc superoxide dismu tase. Results: All layers of the epithelium exhibited labelling for al l four enzymes, although there were differences in labelling intensiti es and distribution between the enzymes. Wing cells showed more intens e labelling for glutathione peroxidase, glutathione S-transferase (neu tral form) and copper/zinc superoxide dismutase than did basal and sup erficial cells. The strongest immunoreactivity was detected for glutat hione S-transferase (acidic) and was equally strong in the superficial and wing cells. Wing cells demonstrated more immunoreactivity in the cell nuclei with antibodies against all four enzymes. A high degree of labelling was also observed in the microplicae and actin cortex of th e superficial cells. Leukocytes, fibroblasts, endothelial cells and er ythrocytes within the stroma exhibited minimal labelling. Conclusion: The subtle changes in distribution of antioxidant enzymes in the norma l human conjunctival epithelium most probably reflect exposure to free radicals in the tear film and are based on the different proliferativ e and functional activities of each of the anatomical layers.