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Characterization of porcine UL16‐binding protein 1 endothelial cell surface expression
Author(s) -
Lilienfeld Benjamin G.,
Schildknecht Anita,
Imbach Lukas L.,
Mueller Nicolas J.,
Schneider Mårten K. J.,
Seebach Jörg D.
Publication year - 2008
Publication title -
xenotransplantation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.052
H-Index - 61
eISSN - 1399-3089
pISSN - 0908-665X
DOI - 10.1111/j.1399-3089.2008.00453.x
Subject(s) - xenotransplantation , tumor necrosis factor alpha , microbiology and biotechnology , biology , antibody , monoclonal antibody , human cytomegalovirus , receptor , cell , cell culture , immune system , immunology , transplantation , medicine , biochemistry , virus , genetics
Background: Natural killer (NK) cells participate in the immune response against solid organ allo‐ and xenografts and are tightly regulated through signals mediated by inhibiting and activating receptors expressed on their cell surface. Human NK cytotoxicity against porcine endothelial cells (pEC) is mediated by the interaction of the activating human NK receptor hNKG2D and its corresponding ligand on pEC, porcine UL‐16 binding protein 1 (pULBP1). The aim of the present study was to characterize the regulation of pULBP1 cell‐surface expression on primary porcine aortic endothelial cells (PAEC). Methods: A monoclonal antibody (mAb; aE5‐63) directed against pULBP1 was generated by immunizing C57BL/6 mice with the pEC line PEDSV.15, and used in cellular ELISA to determine pULBP1 cell surface expression. PAEC were either left untreated or stimulated with human or porcine cytokines [interferon gamma (IFN‐γ), tumor necrosis factor alpha (TNF‐α)], human serum, cultured under hypoxic conditions, or infected with human or porcine cytomegalovirus (CMV). Results: Neither human nor porcine IFN‐γ stimulation changed pULBP1 expression, whereas both human and porcine TNF‐α stimulation as well as human and porcine CMV infection significantly decreased pULBP1 expression on PAEC. Coculture of PAEC with human serum strongly increased pULBP1 expression depending on the binding of human anti‐pig antibodies. Exposure of PAEC to hypoxia only slightly increased pULBP1 expression. Conclusions: In conclusion, (i) the novel anti‐pULBP1 IgM mAb aE5‐63 represents a useful tool to study pULBP1/hNKG2D‐mediated responses in xenotransplantation, and (ii) the expression of pULBP1, a human‐pig cross‐species functional hNKG2D ligand, on the surface of PAEC is modulated by various stimuli associated with transplantation.