title: Decay-accelerating factor prevents acute humoral rejection induced by low levels of anti-alphaGal natural antibodies.
abstract: BACKGROUND
  Hyperacute and delayed vascular rejection due to natural antibodies (NAb) present major obstacles in pig-to-primate xenotransplantation. Although "supraphysiologic" expression of human complement regulatory proteins (CRPs) can prevent hyperacute rejection in discordant xenogenic recipients, their physiologic role in the homologous setting is undefined. We have evaluated the effect of the absence of decay-accelerating factor (DAF) on cardiac allograft rejection in the presence of different levels of antidonor antibodies (Ab).
  
  
  METHODS
  DAF1-deficient (DAF KO; B6129F2 H-2) mice were used as heart graft donors to alpha1,3-galactosyltransferase deficient (GalT KO; B6, H-2) recipients. Heterotopic heart grafting was performed with or without presensitization. Graft survival, histology, and anti-alphaGal Ab levels were monitored.
  
  
  RESULTS
  DAF knockout (KO) but not wild-type (WT) grafts showed hyperacute or acute humoral rejection in nonsensitized GalT KO mice with low levels of anti-alphaGal IgM NAb. However, humoral rejection of both DAF KO and DAF WT donor grafts occurred in presensitized GalT KO recipients.
  
  
  CONCLUSIONS
  The expression of DAF prevents hyperacute rejection in mice with low titers of anti-alphaGal antibody. These studies demonstrate the physiologic role of DAF in preventing humoral rejection in the presence of low levels of NAb and have implications for transplantation of discordant vascularized xenografts.
authors.affiliation: Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Shimizu
authors.forename: Neal R
authors.initials: NR
authors.lastname: Smith
authors.forename: Guiling
authors.initials: G
authors.lastname: Zhao
authors.forename: Edward
authors.initials: E
authors.lastname: Medof
authors.forename: Megan
authors.initials: M
authors.lastname: Sykes
mesh_terms: D000208:Acute Disease; D000818:Animals; D000906:Antibodies / Q000276:immunology*; D000917:Antibody Formation / Q000276:immunology*; D018958:CD55 Antigens / Q000235:genetics / Q000378:metabolism*; D005690:Galactose / Q000737:chemistry* / Q000276:immunology*; D005700:Galactosyltransferases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D006084:Graft Rejection / Q000276:immunology* / Q000517:prevention & control*; D016027:Heart Transplantation / Q000276:immunology; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D015996:Survival Rate
chemical_list: D000906:Antibodies; D018958:CD55 Antigens; D005700:Galactosyltransferases; D005690:Galactose