Long-term cerebrospinal fluid and blood lymphocyte dynamics after rituximab for pediatric opsoclonus-myoclonus.

Introduction: Opsoclonus-myoclonus syndrome (OMS) is an autoimmune paraneoplastic disorder characterized by B and T cell abnormalities in cerebrospinal fluid (CSF) and propensity for relapse. The study aim was to assess whether rituximab-induced B cell ablation in CSF outlasts repopulation in blood and if there are changes in other lymphocyte subsets.

Materials And Methods: In 25 children with OMS, the expression of CSF and blood lymphocyte surface antigens was evaluated by flow cytometry before and at intervals after rituximab therapy.

Results: The reduction in CSF CD27+ memory, CD38+ activated, CD5+, and other B cell subsets was profound (p < 0.0001), comparable across groups (-94%), and sustained over 12-18 months despite repopulation in blood. The observed lag in memory B cell pool recovery in the CSF compared to peripheral blood may be clinically relevant. T cell phenotypic changes involved frequency, not absolute counts, and were transient. Co-treatment with IVIg or ACTH did not significantly alter B cell depletion or repletion.

Discussion: These data indicate that rituximab affords long-term protection against CSF B cell expansion in OMS (ClinicalTrials.gov NCT00244361).