Expression of Galα(1,3)Gal by porcine islet cells and its relevance to xenotransplantation

Abstract

Abstract: In pig‐to‐human transplantation, one of the major obstacles is the expression of Galα(1,3)Galactose by the endothelium of vascularized human tissues and the presence in all humans of IgG and IgM antibodies to this epitope: xenotransplantation would be followed by hyperacute rejection (HAR). However, the findings in endothelial cells of all vessels and the parenchyma of tissues such as kidney and liver do not extend to islet cells. Histological studies demonstrate that the adult pig islet (apart from endothelial cells) does not express Galα(1,3)Gal, nor do fresh neonatal or fetal pig islet cells; after tissue culture (under a variety of conditions) large amounts of Galα(1,3)Gal are expressed by the pig islet cells. However, double staining studies show that Gal+ cells do not secrete insulin, glucagon, or somatostatin and these cells may be spared from potential antigen antibody‐mediated rejection after transplantation. The relevance of Gal expression in islet cells is discussed–short term studies–preferably in pig to Old World Monkey transplants could provide the answer to the relevance of Galα(1,3)Gal expression in islet cells. Thus far it appears that some islets can be destroyed by antibody; others are spared and it is important to determine the nature of the sparing mechanism.