Abstract
Abstract: :
Purpose:The immune privilege of the eye is characterized by the lack of APCs. However, they were detected even in the center of normal murine corneas by a new approach for surface-parallel slicing of the corneal stroma. Topical dexamethasone pretreatment and ballistic gene transfer were studied for their effect on the number of corneal APCs and graft survival after keratoplasty. Methods:The epithelium was removed with EDTA, and frozen sections of the remaining stroma were sliced parallel to the outer surface of the vaulted cornea on a frozen tissue tek log. The central 2.5 mm of these sections and the epithelial flatmounts were examined immunohistologically for F4/80+ cells and MHC class II+ cells in 3 groups of 6 BALB/c mice each. Graft survival after orthotopic keratoplasty (donors: C3H mice, recipients: BALB/c mice) was determined in the same groups: 1. No treatment (controls), 2. Topical dexamethasone pretreatment for 7 days, 3. Gene gun treatment 24 hours before transplantation. Results:The untreated corneas had 115.7±33.7 F4/80+ and 106.8±46.2 MHCII+ cells in the epithelium and 48.9±13.2 F4/80+ and 7.3±5.5 MHCII+ cells in the stromal layer. Dexamethasone pretreatment reduced the positive cells in the epithelial flatmounts (1.8±0.6 F4/80+ and 2±1.7 MHCII+ cells) but not in the corneal stroma. Graft survival was 16±4 days in untreated mice and 16±3 days after dexamethasone pretreatment. Ballistic gene transfer increased the stromal F4/80+ cells (164±91.6, p<0.01). Graft survival after gene gun transfection of donor and recipient corneas with mIL-4 and mCTLA4 (27±19 days) was the same as in the untreated group (27.4±16.8 days) but significantly increased to 64±28 days (p<0.01) when treating only the recipient. Conclusion:The outcome of corneal transplantations is determined by APCs. Ballistic gene transfer triples the F4/80+ cells in the corneal stroma. The favorable effect of gene statement is counteracted by allogen augmentation when the donor cornea is treated. Thus ballistic gene transfection of the corneal epithelium with mIL-4 + mCTLA4 is only effective when restricted to the recipient. Steroid pretreatment dramatically reduces the epithelial but not the stromal APCs and has no influence on graft survival.
Keywords: 607 transplantation • 433 immune tolerance/privilege • 419 gene transfer/gene therapy