Association of serum polyclonal anti-GM1 IgM and anti-neurofilament antibodies with CSF oligoclonal bands in a young with amyotrophic lateral sclerosis

INTRODUCTION: The significance of the association of motor neuron syndromes with anti-GM1 antibodies remains unclear. We report the immunological study of a juvenile case of amyotrophic lateral sclerosis (ALS). MATERIALS AND METHODS: Serum anti-Gm1 and anti-neurofilament antibodies were assayed by ELISA and western blotting and cerebrospinal fluid (CSF) isoelectrofocusing was performed. Immunocytochemical studies were carried out with the patient's serum and CSF on human brain and spinal cord sections. RESULTS: Serum polyclonal IgM anti-GM1, anti-neurofilament antibodies and CSF oligoclonal bands were detected. Furthermore, an in vitro production of anti-GM1 IgM was demonstrated. Immunocytochemical studies showed cytoplasm motor neuron immunostaining, due to both IgG and IgM, that substantially decreased after immunoabsorption of the serum with bovine neurofilament proteins but not with GM1-containing liposomes. No immunostaining was obtained with CSF. Immunosuppressive treatment with cyclophosphamide and two cycles of plasma exchanges lowered anti-GM1 antibody levels, but did not determine any clinical improvement. CONCLUSION: To our knowledge, this is the first report of ALS, associated with circulating levels and in vitro production of polyclonal IgM anti-GM1, anti-neurofilament antibodies and CSF oligoclonal bands. These findings suggest the occurrence in our patients of an autoimmune process that could be involved in the pathogenesis of ALS.