PURPOSE: Keratocytes undergo apoptosis during various pathologic conditions and after exposure to ultraviolet radiation (UVR). It was reported that the Fas/Fas ligand system is involved in modulating keratocyte apoptosis. The expression of Fas ligand (FasL) protein was studied in rabbit corneas after photokeratitis induced by different UV wavelengths. METHODS: Six New Zealand albino rabbit corneas were exposed to 280- and 310-nm UVR in 10-nm full wavebands at doses producing biomicroscopically significant keratitis (0.12 J/cm2 for 280 nm and 0.47 J/cm2 for 310 nm). Animals were killed 24 hours after exposure. Immunohistochemistry was performed to localize FasL protein in paraffin sections of rabbit corneas. Primary antibody was polyclonal goat anti-FasL IgG. RESULTS: FasL protein was uniformly detected in epithelial and endothelial layers of all UVR-exposed and control, nonexposed corneas. The positive staining of keratocytes was confined to the anterior stroma of corneas that were exposed to 280-nm UVR. Corneas exposed to 310-nm UVR showed positively stained keratocytes throughout the entire thickness of the stroma. CONCLUSIONS: These data strongly suggest that the Fas/FasL system may play an important role in apoptosis of corneal cells after UVR. The FasL expression in the corneal stroma was more extensive after exposures at 310-nm UVR than at 280-nm UVR.
PURPOSE: Keratocytes undergo apoptosis during various pathologic conditions and after exposure to ultraviolet radiation (UVR). It was reported that the Fas/Fas ligand system is involved in modulating keratocyte apoptosis. The expression of Fas ligand (FasL) protein was studied in rabbit corneas after photokeratitis induced by different UV wavelengths. METHODS: Six New Zealand albino rabbit corneas were exposed to 280- and 310-nm UVR in 10-nm full wavebands at doses producing biomicroscopically significant keratitis (0.12 J/cm2 for 280 nm and 0.47 J/cm2 for 310 nm). Animals were killed 24 hours after exposure. Immunohistochemistry was performed to localize FasL protein in paraffin sections of rabbit corneas. Primary antibody was polyclonal goat anti-FasL IgG. RESULTS:FasL protein was uniformly detected in epithelial and endothelial layers of all UVR-exposed and control, nonexposed corneas. The positive staining of keratocytes was confined to the anterior stroma of corneas that were exposed to 280-nm UVR. Corneas exposed to 310-nm UVR showed positively stained keratocytes throughout the entire thickness of the stroma. CONCLUSIONS: These data strongly suggest that the Fas/FasL system may play an important role in apoptosis of corneal cells after UVR. The FasL expression in the corneal stroma was more extensive after exposures at 310-nm UVR than at 280-nm UVR.