Mouse monoclonal and rabbit polyclonal antibodies prepared to human myelin-associated glycoprotein also react with glycosphingolipids of peripheral nerve

A panel of mouse monoclonal antibodies and rabbit polyclonal antisera that were raised to myelin-associated glycoprotein (MAG) were screened for reactivity with acidic glycolipids from brain and peripheral nerve by enzyme-linked immunosorbent assay (ELISA) and/or a thin-layer chromatogram overlay technique. Seven out of 7 mouse monoclonal antibodies that recognize carbohydrate epitopes in human MAG also reacted with acidic glycolipids from human and cat peripheral nerve, while monoclonal antibodies that react with polypeptide epitopes on MAG did not react with these glycolipids. Rabbit anti-human MAG antisera also strongly reacted with the glycolipids from peripheral nerve, while rabbit antisera raised to rat MAG did not. None of the antibodies reacted with similar glycolipid fractions prepared from adult human brain. Overlay of thin-layer chromatograms revealed that all the mouse and rabbit antibodies showing reactivity with peripheral nerve glycolipids were binding to the same two sphingoglycolipids that react with human anti-MAG IgM paraproteins in neuropathy and with HNK-1 (anti-Leu-7), a mouse IgM monoclonal antibody that identifies a subset of human lymphocytes with natural killer function. Thus, the carbohydrate epitope(s) in MAG which is shared with nerve acidic glycolipids appears to be highly immunogenic in mice and rabbits. Further, it is clear that the antibodies that react with the carbohydrate moieties of human MAG cannot be used as specific probes for this glycoprotein.