Buonomano R, Tinguely C, Rieben R, Mohacsi PJ, Nydegger UE. Quantitation and characterization of anti‐Galα1–3Gal antibodies in sera of 200 healthy persons. Xenotransplantation 1999; 6:173‐180. © Munksgaard, Copenhagen

Abstract: The natural occurrence of complement‐activating anti‐Galαl–3Gal antibodies (anti‐Gal) in human serum is considered as a major obstacle to xenotransplantation. In this study we determined anti‐Gal in sera of 200 healthy volunteers (100 male, 100 female) of different age groups using an IgG‐ and IgM‐isotype specific ELISA. In addition, we used a direct hemagglutination test involving rabbit erythrocytes (E^R), which are known for abundant surface expression of the Galα1–3Gal antigen. The measured arbitrary ELISA units (U) for anti‐Gal ranged from 5 to 204 U (77 ± 47; mean ± 1 SD) for IgM, and from 1 to 162 U(73 ± 32) for IgG. Anti‐E^R hemagglutination titers were between 1: 65536 and 1: 64 (mean 1: 703), with 75% of all serum samples being in the range of 1: 8192–1: 512. Specificity of the tests was determined by immunoabsorption of anti‐Gal on Sepharose‐coupled synthetic Galα1–3Gal antigen, which reduced ELISA as well as agglutination titers by 90% or more. Overall, inter‐individual differences of both anti‐Gal ELISA values and E^R agglutination titers exceeded age‐, gender‐, or ABO‐type related changes. A tendency was found to higher anti‐Gal IgM values in women than in men (P < 0.005 by Student’s t‐test), whereas the gender‐difference for anti‐Gal IgG or E^R titers was not significant. Application of the anti‐Gal ELISA as well as the E^R agglutination assay for pre‐transplant screening of potential pig xenograft recipients is discussed.