Identification of autoantigens in pediatric opsoclonus-myoclonus syndrome.

Pediatric opsoclonus-myoclonus syndrome (OMS) is a rare disease, including eye movement disturbances, muscle jerks, ataxia and developmental disturbances as the main symptoms. In 50% of patients, OMS is associated with a neuroblastoma as a paraneoplastic neurological syndrome. Since autoantibodies have been detected in some patients and OMS patients respond to immunosuppression, an autoimmune etiology has been suspected in OMS. A variety of autoantibodies have been reported in association with OMS. In paraneoplastic OMS, some patients have anti-Hu antibodies, directed against a group of RNA-binding proteins expressed in neurons and tumor cells. Autoantibodies against alpha-enolase and KH-type splicing regulatory protein could also be demonstrated. However, these autoantibodies are not specific for OMS. By contrast, autoantibodies against surface epitopes of cerebellar granular cells and neuroblastoma cells have been demonstrated exclusively in OMS patients, and these autoantibodies have pathogenic effects on neuroblastoma cells. Taken together, OMS is associated with surface-binding autoantibodies with pathogenic effects, indicating a humoral immune-mediated process as the underlying cause for OMS.