MECHANISMS OF GRAFT-REJECTION IN THE TRANSPLANTATION OF RETINAL-PIGMENT EPITHELIAL-CELLS

Purpose: The role of activated retinal pigment epithelium (RPE) cells was investigated in the rejection after subretinal transplantation. Me thods: RPE cells from 7 pigmented rabbits were separated and evaluated regarding their MHC class II expression as the sign of activation. Th e activation of the RPE cells was augmented with a treatment of 1.000 U/ml interferon gamma (IFN-gamma) for 8 days, These cells Here then tr ansplanted into 7 albino rabbits. As control, RPE transplantations wit hout a pretreatment were performed in 7 albino rabbits. Six weeks afte r the transplantation, the transplanted eyes were enucleated and histo logy was performed. Results: In culture, without IFN-gamma addition, 1 1.38 +/- 0.94% of the RPE cells presented MHC class II. After IFN-gamm a treatment, this quantity increased to 78.26 +/- 1.46% of the RPE cel ls. These cells transplanted into the rabbits caused an obvious reject ion in the transplantation area which was verified histologically. The control group presented a transplantation area without signs of rejec tion or inflammation. Conclusion: In culture, some of the adult RPE ce lls are activated, These cells may accelerate the rejection cascade af ter transplantation. An elimination of activated RPE cells from the tr ansplant should be recommended before transplantation.