Figure 1

Synthesis of the α-gal epitope. N-acetyllactosamine is in most mammals converted to the alpha-gal epitope by the gal-transferase. In certain primate species, including humans, N-acetyllactosamine is converted to the H-subtance by the H-transferase and by the A- or B-transferases further on to the epitopes of the AB0 blood groups, i.e. either the A or B substances, respectively. Strategies for xenoacceptance of porcine organs in humans would be removal of the gal-transferase or introduction of the human H-transferase in the transplanted organ.