An anti-major histocompatibility complex class I intrabody protects endothelial cells from an attack by immune mediators.
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.
Doebis
Cornelia
C
Institute of Medical Immunology, Charité Universitätsmedizin Berlin, Monbijoustr. 2a, D-10117 Berlin, Germany.
Schu
Sabine
S
Ladhoff
Juliane
J
Busch
Annette
A
Beyer
Florian
F
Reiser
Jakob
J
Nicosia
Roberto F
RF
Broesel
Sabine
S
Volk
Hans-Dieter
HD
Seifert
Martina
M
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
D000911:Antibodies, Monoclonal; D015395:Histocompatibility Antigens Class I; D007128:Immunoglobulin Fragments; D007155:Immunologic Factors; D007518:Isoantibodies; C516893:OX-18 monoclonal antibody; C055966:immunoglobulin Fv