The sharing of target-epitopes between human anti-ABO hemagglutinating and anti-Pig (xeno) endothelium or anti-Pig thyroglobulin antibodies.

To select congenial pairs between donor-pig and recipient-human for the future xenotransplantation, the levels of xeno-IgM natural antibodies (NAb) were analyzed in healthy subjects and hemodialysis patients by ELISA tests, which target swine-derived crude endothelial cells (P16N) or proteins (thyroglobulin; TG). The total IgM concentration was lower in hemodialysis patients than in healthy subjects, but there was no difference in IgM NAb titer between the two groups. Individuals with non-B blood types (A, O) exibited significantly higher IgM NAb titer compared with those with B blood types (B, AB). A blood type individuals showed higher killing activity against P16N than those with B, AB or O types with a statistical significance. Sera from A blood type, after being absorbed with red blood cells (RBC) from B blood type, decreased their IgM titer against TG to the level of sera from B blood type. Meanwhile, sera from A blood type significantly decreased hemagglutinin titer against B-RBC after passage through a TG-coated affinity column. We conclude that human anti-B-RBC and anti-Pig xeno NAb have certain common binding epitopes, which might be a branched B carbohydrate structure.