A novel synthesis of α-D-Galp-(1→3)-β-D-Galp-1-Ο-(CH2) 3-NH2, its linkage to activated matrices and absorption of anti-αGal xenoantibodies by affinity columns

Article abstract of DOI:10.1016/S0008-6215(00)00010-0

Pig organs transplanted into primates are rapidly rejected because of the interaction between Galα(1→3)Gal epitopes carried by the graft and natural antibodies (anti-αGal antibodies) present in the blood of the recipient. This report describes a simplified synthesis of the xenogeneic disaccharide and its linkage to activated gel matrices. The digalactosides α-D-Galp-(1→3)-α,β-D-Galp-Galp were synthesized by the condensation of the trichloroacetimidoyl 2,3,4,6-tetra-Ο-benzyl-β-D-galactopyranoside donor with the 3,4-unprotected allyl 2,6-di-Ο-benzyl-α- or β-D-galactopyranoside acceptor precursor. Deallylation and hydrogenolysis led to the free digalactoside, whereas hydrogenolysis alone resulted in the 1-Ο-propyl digalactoside. Both products were tested by inhibition ELISA of natural anti-Gala(1→3)Gal antibodies. The α-D-Galp-(1→3)-β-D-Galp-OPr was found to be the best inhibitor. Thus, the allyl group of the partially benzylated α-D-Galp-(1→3)-β-D-Galp-OAll was engineered, via the hydroxy-, the tosyloxy- and the azidopropyl intermediates, into an aminopropyl group amenable to binding to N-hydroxysuccinimide-activated agarose gel matrices in order to obtain specific immunoabsorption columns. Columns made of gel substituted with 5 μmol of disaccharide per milliliter were found efficient for the immunoabsorption of anti-αGal antibodies from human plasma.