Anti-GD1a ganglioside antibodies in peripheral motor syndromes.

High titers of anti-GD1a antibodies have been found in patients with Guillain-Barre syndrome or motor neuropathy. To determine the possible diagnostic relevance of these antibodies, we measured serum anti-GD1a IgG and IgM antibodies by enzyme-linked immunosorbent assay in 195 patients with different motor syndromes and in 335 control subjects. Moderately high antibody titers (1/1,280-1/5,120) were occasionally found in patients with chronic inflammatory demyelinating polyneuropathy (5%), multifocal motor neuropathy (18%), lower motor neuron disease (3.8%), or amyotrophic lateral sclerosis (1.8%) and in immunological control subjects (1.2%), while titers of 1/20,480 or higher were only found in 2 patients with Guillain-Barre syndrome (IgG in both) and 2 with motor neuropathy and IgM lambda monoclonal gammopathy improving with immunotherapy. In both motor neuropathy patients and the Guillain-Barre syndrome patient who were retested during recovery, anti-GD1a titers decreased concomitantly with clinical improvement. High anti-GD1a antibody titers may be found in several motor syndromes but only markedly increased anti-GD1a titers are strictly associated with potentially treatable dysimmune neuropathies.