CD97-decay-accelerating factor interaction is not involved in leukocyte adhesion to endothelial cells.
BACKGROUND
Effective improvement in xenograft survival is achieved using transplants from transgenic pigs expressing human complement (C) regulatory proteins, including decay-accelerating factor (DAF), CD59, and CD46 on endothelial cells (ECs). The aim of this study was to investigate whether human DAF expression in porcine ECs, as well as regulating C activation, can modify intercellular events through its interaction with its receptor, CD97, on human leukocytes.


METHODS
Cellular interactions between human leukocytes and porcine ECs were investigated in vitro using ECs from either wild-type or DAF-transgenic pigs. Static leukocyte adhesion and T cell activation assays were performed using porcine ECs as target or effector cells, respectively. The role of the DAF-CD97 interaction was investigated using specific blocking monoclonal antibodies (mAbs) against human DAF and its receptor, CD97, in adhesion assays.


RESULTS
Adhesion of U937 or Jurkat T cells, both expressing human DAF and CD97, was quantitatively similar for wild-type and transgenic-DAF-expressing pig ECs. Furthermore, blocking the CD97-DAF interaction did not inhibit xenogeneic leukocyte-endothelium adhesion, whereas blocking the very late antigen 4-vascular cell adhesion molecule-1 pathway reduced this adhesion by 50-80%. Furthermore, DAF and CD97 expression was not up-regulated during tumor necrosis factor-alpha- or lipopolysaccharide-mediated EC activation, unlike the adhesion molecules E-selectin, vascular cell adhesion molecule-1, and intracellular adhesion molecule (ICAM)-1.


CONCLUSIONS
We found that high levels of human DAF expressed on ECs abrogates C-mediated cell damage but did not affect the in vitro adhesive properties or antigen-presenting cell function of genetically modified porcine ECs.
Boulday
Gwénola
G
INSERM U437 Immunointervention en Allo et Xénotransplantation and Institut de Transplantation et de Recherche en Transplantation. C.H.U. de Nantes, 30, bd Jean Monnet, 44093 Nantes Cedex 01, France.
Hamann
Jörg
J
Soulillou
Jean-Paul
JP
Charreau
Béatrice
B
D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology; D015703:Antigens, CD; D018958:CD55 Antigens / Q000032:analysis / Q000502:physiology*; D002448:Cell Adhesion; D002478:Cells, Cultured; D003165:Complement System Proteins / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology*; D006801:Humans; D007962:Leukocytes / Q000502:physiology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000032:analysis / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled; D013552:Swine; D019010:Vascular Cell Adhesion Molecule-1 / Q000502:physiology
C095004:ADGRE5 protein, human; D015703:Antigens, CD; D018958:CD55 Antigens; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; D019010:Vascular Cell Adhesion Molecule-1; D003165:Complement System Proteins