Preparation and Characterization of Antibodies Against a Sulfated Glucuronic Acid‐Containing Glycosphingolipid

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Abstract
In some patients with demyelinating neuropathy there are immunoglobulin M paraproteins that react with carbohydrate determinants shared by myelin‐associated glycoprotein (MAG) and two peripheral nerve acidic glycolipids, termed sulfoglucuronosylglycosphingolipids (SGGLs). To study the antigenicity of these glycolipids, we immunized three New Zealand white rabbits with sulfoglucuronosylparagloboside (SGPG), a major SGGL in peripheral nerve, emulsified in Freund's complete adjuvant and keyhole limpet hemocyanin. All three rabbits inoculated with SGPG showed weight loss and mild weakness, predominantly in their hind feet, 2–5 weeks postinoculation (PI). Two of the three rabbits again showed moderate weakness 3 and 8 months PI, respectively. Electrophysiological studies demonstrated a slowed nerve conduction velocity in the sciatic nerve. Anti‐SGPG antibody titers in sera were detected at dilutions of 1:1,000 to 1:2,500 by an enzyme‐linked immunosorbent assay. Although all three rabbit sera reacted with SGGLs, two reacted with a desulfated form of SGPG and the other did not, suggesting a fine heterogeneity in antigenic specificity. As with sera from patients with demyelinative paraproteinemia, all rabbit sera reacted with MAG in human CNS and PNS myelin. They also reacted with MAG from bovine CNS myelin as well as several low‐molecular‐weight glycoproteins in bovine peripheral nerve myelin. Thus, we demonstrated that the rabbit antisera generated against SGPG have the same or similar antigenic specificity as those of the anti‐MAG M‐proteins from patients with neuropathy. The results suggest that an autoimmune response against the sulfoglucuronosyl residue may participate in the immunopathogenesis of this type of neuropathy.