Rituximab in a patient with multiple sclerosis--effect on B cells, plasma cells and intrathecal IgG synthesis.

OBJECTIVE: To study the time course of immunoglobulin, B and plasma cells in the blood and cerebrospinal fluid (CSF) before and during rituximab treatment in a patient with severe relapsing-remitting multiple sclerosis (MS) in relation to clinical and MRI findings.

METHODS: Immunoglobulins in the CSF were measured by nephelometry and detected by isoelectrical focussing. CSF and blood cell subtypes from seven time points were analysed by flow cytometry.

RESULTS: Treatment with rituximab induced a dramatic and sustained improvement in clinical and MRI findings over a follow-up period of 20 months. By contrast, the initially completely suppressed B and plasma cells in both the blood and CSF reappeared after 5 and 10 months, CSF cells being the first to reappear. Interestingly, intrathecal IgG synthesis persisted throughout the study period.

DISCUSSION: Although highly effective in this case, the clinical effect in larger series and the mechanism of rituximab in MS deserves further evaluation.