Recent studies reported the presence of anti-
ganglioside antibodies in occasional patients with
motor neuron disease. We found polyclonal serum
IgM anti-GM1
antibodies by an anti-GM1
enzyme-linked
immunosorbent assay (ELISA) in 9 (19%) of 48 patients with
motor neuron disease. A comparable frequency of
IgM anti-GM1
antibodies was found in 4 (10%) of 40 sera from patients with other neurological disease. Three (17%) of 18 sera from the patients with
motor neuron disease and 2 (17%) of 12 sera from patients with other neurological diseases had anti-GM1 immunostaining as shown by thin layer chromatography immunoblot. One patient with a lower motor neuron variant of
motor neuron disease or motor axonopathy without multifocal conduction block had a markedly elevated polyclonal
IgM anti-GM1 ELISA titer (greater than 1:64,000) with prominent immunostaining of GM1, moderate immunostaining of GM2, and weak and inconsistent immunostaining of GD1b by thin layer chromatography immunoblot. Treatment with
prednisone resulted in clinical improvement despite increasing anti-GM1 antibody titers. These data indicate that patients with
motor neuron disease have measurable levels of anti-
ganglioside antibodies as frequently as patients with other neurological diseases. This contrasts with a small subgroup of patients with a lower motor neuron variant of
motor neuron disease or motor axonopathy who have markedly elevated levels of serum anti-
ganglioside antibodies and a clinical syndrome that is treatable with immunosuppression.