Abstract
Purpose: :
Antigen presenting cells (APC) participate in chronic or acute graft rejection after keratoplasty. We could recently show that the method we developed for crosslinking of stromal collagen fibrils also leads to apoptosis in keratocytes. The possible elimination of APC by this crosslinking technique was examined.
Methods: :
In 69 enucleated porcine eyes the epithelium was removed. The eyes were wetted with 0.1% riboflavin in 20% dextran solution and irradiated with ultraviolet light (370 nm, 3mW/cm²) for 30 min by two UV–diodes. Additionally 6 eyes were irradiated with intact epithelium and 6 untreated eyes served as controls. After irradiation the corneoscleral buttons were excised and cultured in medium MEM + 2% FCS for 1, 2, 3, 6, 8, 12 d. After respective incubation times, paraffin– and cryosections were analysed by (immuno–)histochemical staining for DAPI and CD45.
Results: :
Within 3d after riboflavin/UV–treatment the number of CD45–positive cells was completely eliminated in the central and peripheric corneae. 6d after irradiation first CD45–positive cells invaded the corneal stroma. 8d after irradiation the CD45+–cell invasion reached its highest level, while at the same time an intensified cell proliferation could be observed in the corneal limbus. By 12d the number of invaded CD45–positive cells reduced to that of untreated control corneas.
Conclusions: :
Additionally to the elimination of keratocytes, the established crosslinking technique resulted in an elimination of CD45–positive cells in the cornea. This technique may be used to immuno–modulate donor corneas in order to reduce the risk of graft rejection.
Keywords: cornea: stroma and keratocytes • immunomodulation/immunoregulation • immunohistochemistry