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 whetherthe drug influences the cellular composition in the cerebrospinalfluid (CSF).Methods:A cross-sectional study examining the cellular composition in blood and cerebrospinalfluid (CSF) from10 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 MSpatients (p=0.0007), and the reduction correlated with treatment duration (rs=−0.75,p=0.021). In theCSF, the absolute number of mononuclear cells were significantly lower in DMF-treated patients compared to theother 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 bothblood and CSF.