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Watier, H ; Guillaumin, JM ; Piller, F ; Lacord, M ; Thibault, G ; Lebranchu, Y ; Monsigny, M ; Bardos, P

Removal of terminal a-galactosyl residues from xenogeneic porcine endothelial cells - Decrease in complement-mediated cytotoxicity but persistence of IgG1-mediated antibody-dependent cell-mediated cytotoxicity

Transplantation 62 (1) 105-113

par Administrateur - publié le

Abstract :

To determine the role of the terminal a-galactosyl residue in the endothelial damage mediated by human xenoreactive natural antibodies (IgM and IgG), we treated porcine endothelial cells in culture with green coffee bean a-galactosidase. A practically complete removal of terminal a-Gal residues (as evaluated by flow cytometry with Bandeiraea simplicifolia isolectin B4) and concomitant exposure of N-acetyllactosamine were obtained without altering cell viability. A dramatic decrease in IgM and IgG binding (from a pool of human sera) was observed, confirming the key role of the a-galactosyl residues. The enzyme treatment did not induce any nonspecific immunoglobulin binding sites, but led to the exposure of new epitopes for a minor fraction of IgM. The main residual IgM and IgG binding could be due to xenoantigens other than the a-galactosyl residues.