Figure 1. Selective increase of plasmablasts (PBs) during relapse of NMO.

(A) B-cell subpopulation analysis by flow cytometry. Peripheral blood mononuclear cell (PBMC) and cerebrospinal fluid (CSF) cells were obtained during relapse of neuromyelitis optica (NMO) or multiple sclerosis (MS) and were stained with fluorescence-conjugated anti-CD19, -CD27, -CD38, and -CD180 monoclonal antibodies (mAbs). PB cells (CD19^intCD27^high) were encircled after observing that they also bear the phenotype of CD38^highCD180⁻ (Figure S1). Values represent the percentages of PB cells among all mononuclear cells.

(B) The proportion of PB and memory B-cells (mB) in PBMC and CSF from MS and NMO during relapse. The data were obtained from eight patients with MS and five with NMO [*p < 0.05 by Mann–Whitney test; each error bar represents the median ± interquartile range (IQR)].