Anti-ganglioside Antibodies in Patients with IgM Paraproteinemia and Polyneuropathy

IgM fraction of in two patients with IgM paraproteinemia and peripheral neuropathy were shown to bind to human peripheral or central nerve gangliosides by immunostaining of thin layer chromatogram and enzyme-linked immunosorbent assay (ELISA). Sera from both patients did not react with myelin-associated glycoprotein (MAG) which is known to be an antigen for some patients with IgM paraproteinemia and polyneuropathy. One patient's serum, who was diagnosed clinically as polyradiculoneuropathy reacted with a ganglioside, sialosyllactosaminylparagloboside (SLPG) in human peripheral nerve. The immunostaining was specific for K chain type, the same as the patient's paraprotein. Serum from the other patient, who was diagnosed as chronic relapsing ataxic polyneuropathy, reacted with G_<M1> ganglioside. The titers of anti-G_<M1> antibodies, examined by ELISA, decreased when his clinical signs, such as ataxic gait, were improved. In the patients of IgM paraproteinemia, these anti-ganglioside antibodies, anti-SLPG and anti-G_<M1> antibodies, have not been reported previously. These antibodies may play a role in the pathogenesis of neuropathy