The possibility of reducing xenoantigen levels with a novel Gal 3 '-sulfotransferase (GP3ST)

Glycoprotein-3-sulfotransferase (GP3ST) is a key enzyme in downregulating the expression of Galalpha1,3Galbeta1,4GlcNAc-R (the alpha-Gal epitope), via enzymatic competition with an alpha1,3 galactosyltransferase (alpha1,3GT), such as alpha2,6 sialyltransferase (alpha2,6ST). In this study, we report the dominance of GP3ST over alpha1,3GT using transfected pig endothelial cell (PEC) lines. The introduction of the GP3ST gene into PEC suppresses its antigenicity with respect to normal human pooled serum (NHS), including the alpha-Gal epitope and the Hanganutziu-Deicher (HD) antigen, and, in addition, reduces the susceptibility to NHS in complement-mediated cell lysis. Western and lectin blot analyses of the products of parental PEC and its transfectants indicated that proteins smaller than 66 kDa have a diminished reactivity with NHS and the IB4 lectin. The levels of the alpha-Gal epitope in neutral glycosphingolipids were also decreased in the GP3ST transfectants as detected in thin layer chromatography by immunostaining. These data indicate that GP3ST is very effective in reducing xenoepitope levels.