IgG subclass distribution of autoantibodies in pediatric opsoclonus-myoclonus syndrome.

Opsoclonus-myoclonus syndrome (OMS) in children is a rare disorder including a severe eye movement disturbance, myoclonia, ataxia and often developmental retardation. Both OMS forms, idiopathic or neuroblastoma-associated (paraneoplastic), have been suspected to be autoimmune. Recently, autoantibodies have been found in OMS sera. We here show that autoantibodies in OMS, both intracellular and surface binding, belong mainly to the IgG3 subclass, although the total serum IgG3 level is normal. These results support the autoimmune hypothesis and point to a protein autoantigen as antigenic target.

New autoantibodies in pediatric opsoclonus myoclonus syndrome.

Opsoclonus-myoclonus syndrome (OMS) is a rare neurologic disorder comprising the main symptoms of eye-movement disturbances, muscle jerks, and severe ataxia. In children and adults, some cases are associated with a tumor as a paraneoplastic syndrome, whereas in children the paraneoplastic form is almost exclusively associated with neuroblastoma. The detection of autoantibodies in some OMS sera led to the hypothesis that the syndrome is of autoimmune origin. Beside autoantibodies against intracellular proteins, such as anti-Hu, alpha-enolase, and KHSRP, specific binding of autoantibodies to the surface of neuroblastoma cells and cerebellar granular neurons have been found. Antiproliferative and proapoptotic effects of these autoantibodies on neuroblastoma cell lines were noted as well. These results support the concept of a humoral autoimmune process in the pathogenesis of OMS.

Elevated B-cell activating factor BAFF, but not APRIL, correlates with CSF cerebellar autoantibodies in pediatric opsoclonus-myoclonus syndrome.

Childhood opsoclonus-myoclonus syndrome (OMS) occurs idiopathic or, in association with a neuroblastoma, as a paraneoplastic syndrome. Since autoantibodies were identified in some patients, an autoimmune pathogenesis has been suspected. While the newly discovered B-cell activating factors BAFF and APRIL are involved in systemic autoimmune diseases, their association with neuroimmunological diseases is hardly understood. We here investigated the BAFF and APRIL levels in serum and cerebrospinal fluid (CSF) of OMS patients and their correlation with surface-binding autoantibodies. BAFF and APRIL were both determined by ELISA, and autoantibodies to cerebellar granular neurons (CGN) have been investigated by flow cytometry in 17 OMS patients, 16 neuroblastoma (NB) patients, 13 controls and 11 children with inflammatory neurological diseases (IND). BAFF, but no APRIL, was elevated in the CSF of OMS children and IND children. However, in contrast to IND patients, OMS patients did not have a blood-brain-barrier disturbance, indicating that BAFF was produced intrathecally in OMS patients, but not in IND patients. CSF BAFF levels showed a correlation with CSF CGN autoantibodies (r(2)=0.58, p<0.05). These data indicate that an activated B-cell system in the cerebrospinal fluid is involved in the pathogenesis of OMS, and BAFF may be a candidate parameter for the activation of B-cell immune system.

Increased prevalence of autoimmune disorders and autoantibodies in parents of children with opsoclonus-myoclonus syndrome (OMS).

Opsoclonus-myoclonus syndrome (OMS) is a rare neurological disease in childhood which can be associated with neuroblastoma. Since autoantibodies have been detected in some patients with OMS, an autoimmune etiology is suspected. We compared the prevalence of autoimmune disorders and autoantibodies in parents of children with OMS and in a group of controls of same age and sex. Autoimmune diseases were found in 15.8% of the parents of OMS children, but only in 2.0% of the controls (p<0.001) There was also an increased prevalence of autoantibodies in the OMS parents (42.8% vs. 8.0%, p<0.001). Thyroid diseases were the most frequent autoimmune diseases found, followed by inflammatory rheumatic diseases. Interestingly, the OMS parents also had significantly more autoantibodies against CNS structures than the controls (p<0.01). These findings support the autoimmune hypothesis of childhood OMS and may also hint to a genetic susceptibility for OMS.