EFFECTS OF EOSINOPHIL GRANULE PROTEINS ON HUMAN CORNEAL EPITHELIAL-CELL VIABILITY AND MORPHOLOGY

Purpose. There is mounting evidence that eosinophil granule proteins m ay cause tissue injury during allergic inflammation of the eye. Theref ore, the authors investigated the in vitro effects of human eosinophil major basic protein (MBP), eosinophil cationic protein (ECP), eosinop hil peroxidase (EPO), and eosinophil-derived neurotoxin (EDN) on cultu red human corneal epithelial cell viability and morphology. Methods. C onfluent primary human corneal epithelial cell cultures were exposed t o each of the four human eosinophil cationic granule proteins at conce ntrations ranging from 0 to 100 mu g/ml (0, 12.5, 25, 50, and 100 mu g /ml) for up to 48 hours kin serum-free media. Morphologic changes were assessed by light microscopy at 1, 6, 24, and 48 hours; cell viabilit y was measured using the MTT cell viability assay at 24 hours. Results . Cells treated with MBP and ECP induced a dose-dependent gradual incr ease in morphologic changes; in contrast, EPO and EDN induced minimal changes in cell morphology. At 24 hours, both MBP and ECP induced stat istically significant (P < 0.05) decreases in cell viability at a conc entration of 100 mu g/ml: EPO induced a significant (P < 0.05) decreas e in cell viability at all concentrations tested, and EDN showed no si gnificant reduction of cell viability at any of the concentrations tes ted. Conclusions. The current study suggests that the human eosinophil granule proteins MBP and ECP affect human corneal epithelial cell via bility and morphology in vitro, whereas the protein EPO affects cell v iability only. EDN had no significant effect on cell viability or morp hology. Hence, MBP, ECP, and EPO perturb the corneal epithelium differ entially and may contribute to keratopathy associated with severe ocul ar allergy.