The major obstacle to successful discordant kidney xenotransplantation is hyperacute rejection (HAR). Complement plays a key role in the induction of HRA, defined by endothelial cell activation, loss of vascular integrity, hemorrhage and thrombosis. The activation of complement is tightly controlled by a number of species-specific regulatory proteins which inhibit, at different points, the cascade of events leading to the formation of the membrane attack complex (MAC). We have tested the hypothesis that kidneys derived from transgenic mice expressing two human complement inhibitors, Decay Accelerating Factor (hDAF) and Membrane Cofactor Protein (MCP), could be protected from human complement-mediated damage.

Materials and Methods:

Control and transgenic mice were perfused with human plasma by cannulation of the right jugular vein, at a perfusion rate of 10 micro L./min. for two hours. Complement C3 deposition was detected on kidney sections by immunohistochemistry using specific FITC antibody. Complement-induced tissue damage was evaluated by histopathological examination.


Heavy deposition of complement C3 was observed on kidneys derived from perfused control mice. This was associated with a characteristic HAR pathology of severe interstitial hemorrhage, inflammatory reaction, loss of glomerula and tubuli structure. Kidneys derived from mice transgenic for hDAF or hMCP were partially protected from both complement C3 deposition and tissue damage. The expression of both dDAF and hMCP in double transgenic mice significantly increases the protection from human complement-mediated damage.


A novel model of in vivo perfusion with human plasma has been adopted to recreate the initial event of HAR. Our data show that this murine model could be very valuable to determine the effect of transgenic human molecules in protecting vascularized organs from human complement attack.


  • 1 : The regulators of complement activation (RCA) gene cluster. Adv. Immun.1989; 45: 381. Google Scholar
  • 2 : Decay-accelerating factor and membrane cofactor protein. Curr. Top. Microbiol. Immunol.1989; 153: 123. Google Scholar
  • 3 : Presence of human chromosome 1 with expression of human decay-accelerating factor (DAF) prevents lysis of mouse/human hybrid cells by human complement. Scand. J. Immunol.1991; 34: 771. Google Scholar
  • 4 : Membrane Cofactor Protein (CD46) protects cells from complement-mediated attack by an intrinsic mechanism. J. Exp. Med.1992; 175: 1547. Google Scholar
  • 5 : Expression of human Decay Accelerating Factor or Membrane Cofactor Protein genes on mouse cells inhibits lysis by human complement. Transplant. Proc.1992; 24: 474. Google Scholar
  • 6 : Expression of a functional human complement inhibitor in a transgenic pig as a model for the prevention of xenogeneic hyperacute organ rejection. Proc. Natl. Acad. Sci. USA1994; 91: 11153. Google Scholar
  • 7 : Mice transgenic for human CD46 and CD55 are protected from human complement attack. Transplant. Proc.1995; 27: 333. Google Scholar
  • 8 : Livers of mice transgenic for human CD46 are protected from human complement attack. Transgenics1995; 1: 629. Google Scholar
  • 9 : Transgenic expression of human complement regulatory proteins in mice results in diminished complement deposition during organ xenoperfusion. Transplantation1995; 59: 1177. Google Scholar
  • 10 : Tissue expression of human complement inhibitor, decay-accelerating factor, in transgenic pigs: A potential approach for preventing xenograft rejection. Transplantation1995; 59: 1325. Google Scholar
  • 11 : Human complement regulatory proteins protect swine-to-primate cardiac xenografts from humoral injury. Nature Medicine1995; 1: 423. Google Scholar
  • 12 : Characterization of complement-mediated liver damage and protection in control and transgenic mice for human complement blockers MCP and DAF. Transplant. Proc.1996; 28: 127. Google Scholar
  • 13 : Membrane Cofactor Protein (MCP or CD46): Newest member of the regulators of complement activation gene cluster. Ann. Rev. Immunol.1991; 9: 431. Google Scholar
  • 14 : Manipulating the Mouse Embryo: A Laboratory Manual. Cold Spring Harbor, N. Y.: Cold Spring Harbor Lab. Press1986. Google Scholar
  • 15 : The barrier to xenotransplantation. Transplantation1991; 52: 937. Google Scholar
  • 16 : Mechanism of complement activation in the hyperacute rejection of porcine organs transplanted into primate recipients. Am. J. Pathol.1992; 140: 1157. Google Scholar
  • 17 : Human antibodies to pig determinants and their association with hyperacute rejection of xenografts. In: Xenotransplantation: The Transplantation of Organs and Tissues between Species. Edited by . New York: Springer-Verlag.1991. Google Scholar
  • 18 : Histopathology of kidney xenograft rejection. In: Xenotransplantation: The Transplantation of Organs and Tissues between Species. Edited by . New York: Springer-Verlag1991. Google Scholar
  • 19 : Experimental renal heterotransplantation. III Passive transfer of transplantation immunity. Transplantation1967; 5: 514. Google Scholar
  • 20 : Histopathology of hyperacute rejection of the heart: experimental and clinical observations in allografts and xenografts. J. Heart Lung Transplant.1991; 10: 223. Google Scholar

Chiron-Biocine Research Center, Siena, the Ospedale S. Giacomo, Laboratorio di Immunologia, Roma and the II sup o Patologia Chirurgica, Universita “La Sapienza” Roma, Italy.