Serum autoantibodies in childhood opsoclonus-myoclonus syndrome: An analysis of antigenic targets in neural tissues

Objective: Opsoclonus-myoclonus (OM) is a rare neurologic syndrome affecting children and adults. In children it occurs as a parainfectious process or a paraneoplastic syndrome in association with neuroblastoma. Evidence for an immune mechanism includes the presence of serum autoantibodies to several neural antigens and improvement of symptoms with immunosuppressive therapy. We studied the neural antigenic targets of serum IgM and IgG autoantibodies from nine children with OM. Design: We studied sera from nine children with OM, three with associated neuroblastoma and six with a prodromal viral illness. Control subjects (n = 77) included four children with neuroblastoma but not OM, 32 children with other neurologic disorders, and 41 with nonneurologic illnesses. We studied the neural antigenic targets of serum IgM and IgG autoantibodies by the following methods: (1) immunostaining of human cerebellar sections and peripheral nerve, and (2) Western blot analysis with human brain fractions including white matter, gray mailer, and cerebellar Purkinje cells and nuclei. Results: Sera from all nine children with OM had IgM and IgG binding to the cytoplasm of cerebellar Purkinje cells and to some axons in white matter. In peripheral nerve, IgM and IgG from all nine OM sera bound to large and small axons. Western blot analysis showed a distinctive pattern of binding to several neural proteins, including a 210 kd antigen identified as the high molecular weight subunit of neurofilament. No control serum showed a similar pattern of reactivity. Conclusion: Opsoclonus-myoclonus syndrome in childhood is associated with a distinctive pattern of serum IgM and IgG binding to neural tissues and antigens.