Polymorphism in the human anti-pig natural antibody repertoire: implications for antigen-specific immunoadsorption.
BACKGROUND
Anti-Galalpha1-3Gal antibodies cause hyperacute rejection (HAR) in pig-to-primate xenotransplantation. Long-term graft survival has not been achieved despite abrogation of HAR using transgenic pigs. IgG and IgM anti-Galalpha1-3Gal also play a role in the events following abrogation of HAR. Characterizing these antibodies and developing a system for their removal is therefore crucial to future success in xenotransplantation.


RESULTS
We have developed a neoglycoprotein enzyme-linked immunosorbent assay to probe the precise antigenic requirements for the binding of anti-Galalpha1-3Gal and have analyzed 77 normal sera. Sixty-six percent of individuals have IgG that recognizes the Galalpha1-3Gal di-, tri-, and pentasaccharides (D, T, and P, respectively), termed DTP phenotype. The frequency of other phenotypes was - -P, 13%; -TP, 12%; D-P, 8%; and DT-, 1%. The IgG subclasses found were IgG2 (95%), IgG3 (34%), IgG1 (31%), and IgG4 (17%). IgM in 91% of individuals recognized all three antigens. Further antibody heterogeneity was demonstrated when immunoadsorbents derived from Galalpha1-3Galbeta1-4GlcNAcbeta1-3Galbeta1-4Glc (PENTA) were tested. Galalpha1-3Galbeta1-4Glc (TRI 6) or PENTA agarose were effective for IgG removal in all individuals. For IgM removal, two deoxy derivatives were completely successful in 73% of individuals. Combining the Galalpha1-3Gal (DI) and TRI 6 agarose produced an adsorbent that completely removed anti-Galalpha1-3Gal IgG and IgM in all individuals tested.


CONCLUSIONS
Although the polymorphism in the anti-Galalpha1-3Gal repertoire, which we have demonstrated, represents a major obstacle to the development of an effective immunoadsorbent, the combination of DI and TRI 6 agarose appears sufficient for pig-to-human xenotransplantation.
McKane
W
W
The Brent Laboratory, St. Mary's Hospital, London, United Kingdom.
Lee
J
J
Preston
R
R
Hacking
A
A
Simpson
P
P
Lynds
S
S
Goldberg
L
L
Cairns
T
T
Taube
D
D
D000818:Animals; D000910:Antibodies, Heterophile / Q000235:genetics*; D000916:Antibody Diversity; D004187:Disaccharides / Q000276:immunology*; D000939:Epitopes / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000235:genetics / Q000276:immunology; D007164:Immunosorbents / Q000276:immunology; D010641:Phenotype; D011110:Polymorphism, Genetic; D013552:Swine / Q000276:immunology*; D014183:Transplantation, Heterologous
D000910:Antibodies, Heterophile; D004187:Disaccharides; D000939:Epitopes; D007074:Immunoglobulin G; D007164:Immunosorbents; C055075:galactosyl-(1-3)galactose