Profiling of B cells and their subsets by whole blood gene expression analysis versus flow cytometry in multiple sclerosis

We investigated if differentially expressed mRNA targets could be used as surrogate markers for circulating B cells and subsets. In paired blood samples from patients with untreated, anti-CD20-treated, fingolimod-treated, and natalizumab-treated multiple sclerosis, whole blood expression of CD19 correlated with B cell counts determined by flow cytometry, ROR1 with transitional B cells, TCL1A and ZNF727 with naïve B cells, NEXMIF with memory B cells and BCMA with plasmablasts. CD19 expression distinguished patients with B cell repletion and may be used as an alternative to flow cytometry, but NEXMIF was unsuitable for memory B cell monitoring in rituximab-treated patients.