B Lymphocyte Subset Changes in Primary Membranous Nephropathy

Primary membranous nephropathy (PMN) is an autoimmune disease affecting renal glomerulus, characterized by autoantibodies aggregation on podocytes and subsequent epithelial thickening. Therefore, rituximab, an anti-CD20 monoclonal antibody, is used to treat patients with the deteriorating condition.

Assuming that rituximab demolishes a considerable number of B-lymphocytes and causes transient immunodeficiency, we aimed to identify B cell subsets involved in PMN pathogenesis to facilitate specific targeting.

Using flowcytometery, 25 PMN patients including 15 on standard treatment and 10 on standard treatment plus rituximab were enrolled to compare with healthy controls. Rituximab-receiving patients were studied before and two months after administration.

Neither total CD19+ nor memory B cell percentages showed significant differences between the study groups. However, the number of B regulatory cells (Breg) was lower in both standard-treatment and Rituximab-receiving patients than in controls. Moreover, the percentage of naïve/mature B cells dropped after standard treatment.

PMN patients seem to possess an insufficient percentage of Breg cells, which are involved in immunomodulation. Furthermore, the standard-treatment group showed a reduced count of naïve/mature B cells, which constitute a substantial proportion of normal B lymphocytes population.