B-cell composition in the blood and cerebrospinal fluid of multiple sclerosis patients treated with dimethyl fumarate

Abstract

Background B cells may contribute to the immunopathogenesis of multiple sclerosis (MS). Dimethyl fumarate (DMF) has recently been shown to reduce the frequency of memory B cells in blood, but it is not known whether the drug influences the cellular composition in the cerebrospinal fluid (CSF). Methods A cross-sectional study examining the cellular composition in blood and cerebrospinal fluid (CSF) from 10 patients treated with DMF and 18 patients receiving other disease modifying drugs or no treatment. Results Patients treated with DMF had reduced proportions of memory B cells in blood compared to other MS patients (p = 0.0007), and the reduction correlated with treatment duration (rs = −0.75, p = 0.021). In the CSF, the absolute number of mononuclear cells were significantly lower in DMF-treated patients compared to the other patients (p = 0.023), and there was a disproportionate decrease of plasmablasts (p = 0.031). Conclusion The results of this exploratory study support a B-cell mediated mechanism of action for DMF in both blood and CSF.