Abnormal expression of alpha-galactosyl epitopes in man. A trigger for autoimmune processes?
1% of circulating IgG in man is anti-Gal antibody, which interacts specifically with the carbohydrate structure Gal alpha 1----3Gal beta 1----4GlcNAc-R on mammalian glycoconjugates (described throughout as the alpha-galactosyl epitope). This epitope is abundant on cell surface glycoconjugates of non-primate mammals, prosimians, and New World monkeys. It is not found on cells of Old World monkeys, apes, and man because of diminished alpha 1----3 galactosyltransferase enzyme activity. However, the alpha 1----3 galactosyltransferase gene seems to be present within the human genome. A mechanism that increases alpha 1----3 galactosyltransferase activity in human cells could trigger an autoimmune process mediated by anti-Gal binding to the newly synthesised alpha-galactosyl epitopes.
Galili
U
U
MacMillan-Cargill Hematology Research Laboratory, Cancer Research Institute, San Francisco, California.
D000818:Animals; D001323:Autoantibodies / Q000032:analysis*; D001327:Autoimmune Diseases / Q000201:enzymology*; D005075:Biological Evolution; D000939:Epitopes / Q000032:analysis*; D005700:Galactosyltransferases / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D005808:Genes, Recessive; D006001:Glycoconjugates / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000032:analysis*; D013489:Suppression, Genetic
D001323:Autoantibodies; D000939:Epitopes; D006001:Glycoconjugates; D007074:Immunoglobulin G; D005700:Galactosyltransferases