title: Mechanisms of graft rejection in the transplantation of retinal pigment epithelial cells.
abstract: OBJECTIVE
  The role of activated retinal pigment epithelium (RPE) cells was investigated in the rejection after subretinal transplantation.
  
  
  METHODS
  RPE cells from 7 pigmented rabbits were separated and evaluated regarding their MHC class II expression as the sign of activation. The activation of the RPE cells was augmented with a treatment of 1,000 U/ml interferon gamma (IFN-gamma) for 8 days. These cells were then transplanted into 7 albino rabbits. As control, RPE transplantations without a pretreatment were performed in 7 albino rabbits. Six weeks after the transplantation, the transplanted eyes were enucleated and histology was performed.
  
  
  RESULTS
  In culture, without IFN-gamma addition, 11.38 +/- 0.94% of the RPE cells presented MHC class II. After IFN-gamma treatment, this quantity increased to 78.26 +/- 1.46% of the RPE cells. These cells transplanted into the rabbits caused an obvious rejection in the transplantation area which was verified histologically. The control group presented a transplantation area without signs of rejection or inflammation.
  
  
  CONCLUSIONS
  In culture, some of the adult RPE cells are activated. These cells may accelerate the rejection cascade after transplantation. An elimination of activated RPE cells from the transplant should be recommended before transplantation.
authors.affiliation: Department of Ophthalmology, Faculty of Medicine, University of Leipzig, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Kohen
authors.forename: V
authors.initials: V
authors.lastname: Enzmann
authors.forename: F
authors.initials: F
authors.lastname: Faude
authors.forename: P
authors.initials: P
authors.lastname: Wiedemann
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use; D002478:Cells, Cultured; D004195:Disease Models, Animal; D005500:Follow-Up Studies; D005802:Genes, MHC Class II / Q000276:immunology; D006084:Graft Rejection / Q000276:immunology* / Q000473:pathology / Q000517:prevention & control; D006085:Graft Survival / Q000276:immunology; D007371:Interferon-gamma / Q000627:therapeutic use; D010857:Pigment Epithelium of Eye / Q000276:immunology / Q000473:pathology / Q000637:transplantation*; D011817:Rabbits; D012160:Retina / Q000473:pathology / Q000601:surgery*
chemical_list: D000970:Antineoplastic Agents; D007371:Interferon-gamma