title: An anti-major histocompatibility complex class I intrabody protects endothelial cells from an attack by immune mediators.
abstract: OBJECTIVE
  In vitro endothelialization has significantly improved the overall outcome of artificial prostheses in cardiovascular bypass surgery. A drawback of this tissue-engineering method remains the limited availability of suitable autologous endothelial cells (EC), especially in aged patients. Allogeneic EC with high proliferative capacity represent a potentially valuable alternative to a patient-specific vascular transplant. However, such cells carry the risk of being rejected due to Major Histocompatibility Complex (MHC) mismatches.
  
  
  METHODS
  We investigated the effects of a very potent, intracellularly expressed antibody directed against MHC class I molecules, referred to as alpha-rat MHC I single chain variable fragment (sFv) intrabody. The intrabody was stably expressed in rat aortic EC (RAEC) following lentiviral vector-mediated gene transfer. The functional consequence of the MHC I down-regulation was tested in an allogeneic setting in two different in vitro assays.
  
  
  RESULTS
  Stable expression of the alpha-rat MHC I sFv intrabody resulted in a highly efficient depletion of surface MHC I. Thereby those RAEC which displayed low MHC I levels over extended periods of time were protected against killing by allo-specific, cytotoxic T cells (CTL) and by allo-antibody/complement-mediated lysis.
  
  
  CONCLUSIONS
  These results demonstrate that intrabody-mediated down-regulation of MHC I reduces the immunogenicity of RAEC which may provide a suitable alternative supply for the lining of vascular prostheses.
authors.affiliation: Institute of Medical Immunology, Charité Universitätsmedizin Berlin, Monbijoustr. 2a, D-10117 Berlin, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Doebis
authors.forename: Sabine
authors.initials: S
authors.lastname: Schu
authors.forename: Juliane
authors.initials: J
authors.lastname: Ladhoff
authors.forename: Annette
authors.initials: A
authors.lastname: Busch
authors.forename: Florian
authors.initials: F
authors.lastname: Beyer
authors.forename: Jakob
authors.initials: J
authors.lastname: Reiser
authors.forename: Roberto F
authors.initials: RF
authors.lastname: Nicosia
authors.forename: Sabine
authors.initials: S
authors.lastname: Broesel
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Volk
authors.forename: Martina
authors.initials: M
authors.lastname: Seifert
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics; D003602:Cytotoxicity, Immunologic; D015536:Down-Regulation; D042783:Endothelial Cells / Q000276:immunology*; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology*; D007128:Immunoglobulin Fragments / Q000235:genetics; D007155:Immunologic Factors / Q000276:immunology*; D007424:Intracellular Fluid / Q000276:immunology; D007518:Isoantibodies / Q000276:immunology; D051381:Rats; D018709:Statistics, Nonparametric; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D014161:Transduction, Genetic / Q000379:methods; D014184:Transplantation, Homologous
chemical_list: D000911:Antibodies, Monoclonal; D015395:Histocompatibility Antigens Class I; D007128:Immunoglobulin Fragments; D007155:Immunologic Factors; D007518:Isoantibodies; C516893:OX-18 monoclonal antibody; C055966:immunoglobulin Fv