title: Vascular endothelial cell apoptosis induced by anti-donor non-MHC antibodies: a possible injury pathway contributing to chronic allograft rejection.
abstract: BACKGROUND
  Non-major histocompatibility complex (non-MHC) alloantibodies may play a pathogenic role in chronic rejection but remain poorly characterized.
  
  
  METHODS
  The kinetics of alloantibody production and the mechanism by which non-MHC alloantibodies cause graft injury were investigated in a Lewis-to-Fischer 344 (LEW-to-F344) rat model of cardiac transplantation.
  
  
  RESULTS
  Flow cytometry detected that all the F344 recipients of LEW allografts produced anti-donor immunoglobulin G (IgG) antibodies reactive with LEW lymphocytes and endothelial cells. A sub-group of recipients that rejected their grafts in 30 to 60 days exhibited markedly increased levels of anti-donor IgG antibodies (n = 6, mean fluorescence intensity [MFI]:23.85 +/- 2.7) than recipients with long-surviving allografts (n = 4, MFI:11.23 +/- 0.81; p = 0.00058). Passive transfer of anti-donor sera induced chronic rejection of LEW heart allografts in an immune non-responsiveness model of F344 rats induced by intrathymic inoculation of donor-specific lymphocytes. Immunoglobulin G antibodies purified from the anti-LEW sera exhibited complement-dependent cytotoxicity against LEW vascular endothelial cells in flow-cytometric cytotoxicity assay. The targeted endothelial cells displayed early (annexin V+) and late (TUNEL+) evidence for programmed cell death. Western blot analysis of poly (ADP-ribose) polymerase (PARP) demonstrated that the 25-kD PARP-cleavage fragment was present at the lysates of the vascular endothelial cells treated with anti-donor IgG antibodies, indicating apoptosis-associated caspase activity in these cells. In situ teminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining demonstrated that vascular endothelial cell apoptosis was consistently present in all LEW heart allografts with chronic rejection.
  
  
  CONCLUSIONS
  Non-MHC alloantibodies are pathogenic and capable of causing chronic graft injury through an antibody-induced cell apoptosis mechanism. The results emphasize the importance of non-MHC antibodies as a common predisposing factor in the development of chronic rejection.
authors.affiliation: Department of Cardiothoracic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, 90033, USA. gdw@.usc.edu
authors.forename: Gordon D
authors.initials: GD
authors.lastname: Wu
authors.forename: Yang-Sun
authors.initials: YS
authors.lastname: Jin
authors.forename: Roberto
authors.initials: R
authors.lastname: Salazar
authors.forename: Wang-De
authors.initials: WD
authors.lastname: Dai
authors.forename: Natasha
authors.initials: N
authors.lastname: Barteneva
authors.forename: Mark L
authors.initials: ML
authors.lastname: Barr
authors.forename: Lura W
authors.initials: LW
authors.lastname: Barsky
authors.forename: Vaughn A
authors.initials: VA
authors.lastname: Starnes
authors.forename: Donald V
authors.initials: DV
authors.lastname: Cramer
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology*; D003601:Cytotoxicity Tests, Immunologic; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology*; D005434:Flow Cytometry; D006084:Graft Rejection / Q000276:immunology*; D016027:Heart Transplantation / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D007518:Isoantibodies / Q000097:blood*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D011917:Rats, Inbred Lew; D014184:Transplantation, Homologous
chemical_list: D007074:Immunoglobulin G; D007518:Isoantibodies