Comparison of B lymphocyte profile between membranous nephropathy and idiopathic nephrotic syndrome pediatric...

Membranous nephropathy (MN) and idiopathic nephrotic syndrome (INS) are two B-cell mediated rare glomerular diseases that benefit from treatment with B-cell depleting anti-CD20 monoclonal antibody rituximab. Different B-cell dysregulations have been described in pediatric INS patients and in adults affected by MN. In adult MN patients, an increased level of mature-naïve cells and atypical memory B cells and a significant reduction in IgM memory and switched memory B cells have been previously described compared to healthy individuals. To date, there is no information available about B-cell immunophenotyping in pediatric MN.

In this monocentric retrospective case-control study, we analyzed by flow cytometry the B-cell profile in rituximab-naïve (n = 15) children affected by MN, compared with pediatric INS patients (n = 15) selected by propensity score matching, and both evaluated during active disease. Age-matched controls (n = 15) with non-immune-mediated kidney diseases were also characterized. Demographical, clinical, laboratory, and immunosuppressive treatment data were registered.

We found that children with MN and INS had significantly higher circulating levels of total CD19⁺, mature-naïve, and atypical memory B cells and similar levels of transitional B cells when compared to age-matched controls. Circulating levels of total memory B cells, IgM memory B cells, and plasmablasts/plasmacells were significantly higher in INS patients compared to both MN patients and age-matched controls.

Our study indicated that children affected by MN had a specific B-cell profile and that high levels of memory B-cell subsets are specific to INS pediatric patients independently of proteinuria intensity.