Immunophenotyping of CSF lymphocytes

Background: Although many lines of evidence suggest an autoimmune etiology, the pathophysiology of opsoclonus–myoclonus syndrome (OMS) remains poorly understood and no immunologic abnormalities have correlated with neurologic severity. Conventional immunotherapies often do not prevent relapse or permanent sequelae. Objective: To test the cellular immune hypothesis of OMS in a cross-sectional study and determine if CSF lymphocyte subset analysis provides biomarkers of disease activity. Methods: The expression of lymphocyte surface antigens was investigated in CSF and blood of 36 children with OMS and 18 control subjects, using a comprehensive panel of monoclonal antibodies to adhesion and activation proteins in combination with anti-CD3 and anti-CD45 antibodies in four-color fluorescenceactivated cell sorting. Results: Although most children with OMS had normal CSF cell counts, they exhibited expansion of CD19 B-cell (up to 29%) and T-cell (up to 26%) subsets and a lower percentage of CD4 T-cells and CD4/CD8 ratio, which persisted even years after disease onset and conventional treatments. The percentage of activated CSF T-cells was also higher. Abnormalities correlated with neurologic severity, as scored blinded from videotapes using a 12-item motor scale, and disease duration. No significant differences were found between tumor and no-tumor groups. In children with neuroblastoma, tumor resection or cancer chemotherapy did not alter immunologic abnormalities. Conclusions: CSF Band T-cell recruitment is linked to neurologic signs in pediatric OMS, which may relate to relapses and disease progression. NEUROLOGY 2004;62:1526–1532 Opsoclonus–myoclonus syndrome (OMS) is a neuropsychiatric disorder,1 in which autoimmunity may play an important role, characterized by relapses2 and often permanent sequelae.3,4 The brainstem and cerebellum are thought to give rise to the principal motor features.3,5-7 In children, neuroblastoma8 and viral infections9,10 are the most common causes.11 The immunopathophysiology of childhood OMS has remained rather elusive. Basic information about the participant immune cell types in OMS is lacking, and there have been no convincing links between various autoantibodies6,12,13 and neurologic abnormalities. Because autoantibodies are not found in all cases and they do not cause OMS in laboratory animals when passively transferred from humans, we hypothesized cellular immune co-involvement.14 The same immune cell types involved in host tumor defenses, such as tumor-infiltrating lymphocytes and lymphokine-activated killer cells, could participate in the paraneoplastic syndrome through blood–brain barrier permeation after activation by onconeural antigens. Lymphocytes traffic from brain capillaries through the CNS as part of a physiologic process of immune surveillance.15 Under various pathologic conditions, CSF can host increased numbers of T-cells (helper/inducer; cytotoxic/suppressor), T-cells, B-cells, natural killer (NK) cells, as well as cell types not normally found in CSF, Additional material related to this article can be found on the Neurology Web site. Go to www.neurology.org and scroll down the Table of