Expression of human alpha-galactosidase and alpha1,2-fucosyltransferase genes modifies the cell surface Galalpha1,3Gal antigen and confers resistance to human serum-mediated cytolysis.

OBJECTIVE: To explore the strategies which reduce the amount of xenoantigen Galalpha1,3Gal.

METHODS: Human alpha-galactosidase gene and alpha1,2-fucosyltransferase gene were transferred into cultured porcine vascular endothelial cells PEDSV.15 and human alpha-galactosidase transgenic mice were produced. The Galalpha1,3Gal on the cell surface and susceptibility of cells to human antibody-mediated lysis were analyzed.

RESULTS: Human alpha-galactosidase gene alone reduced 78% of Galalpha1,3Gal on PEDSV.15 cell surface while human alpha-galactosidase combined with alpha1,2-fucosyltransferase genes removed Galalpha1,3Gal completely. Decrease of Galalpha1,3Gal could reduce susceptibility of cells to human antibody-mediated lysis, especially during co-expression of alpha-galactosidase gene and alpha1,2-fucosyltransferase gene. RT-PCR indicated positive human alpha-galactosidase gene expression in all organs of positive human alpha-galactosidase transgenic F1 mice including heart, liver, kidney, lung, and spleen, the amount of Galalpha1,3Gal antigens on which was reduced largely. 58% of spleen cells from F1 mice were destroyed by complement-mediated lysis compared with 24% of those from normal mice.

CONCLUSIONS: Human alpha-galactosidase gene and alpha1,2-fucosyltransferase gene effectively reduce the expression of Galalpha1,3Gal antigens on endothelial cell surface and confers resistance to human serum-mediated cytolysis. The expression of human alpha-galactosidase in mice can also eliminate the Galalpha1,3Gal antigens in most tissues and decrease the susceptibility of spleen cells to human serum-mediated cytolysis.