Membranous nephropathy (MN) is the most frequent cause of nephrotic syndrome (NS) in adults. The majority of MN patients show detectable circulating antibodies against the M-type phospholipase A2 receptor (PLA2R). Infusion of anti-CD20 monoclonal antibodies results in a profound depletion of B-cells, which are thought to be responsible for anti-PLA2R production. B-cell depletion is followed by NS remission in 70% of cases. Limited evidence highlighted that differences in the B- and T-cell compartments may exist between responders and non-responders. Owing to the non-homogenous efficacy of anti-CD20 treatment, investigators hypothesize that in MN patients who experience NS remission after B-cell depleting therapy, autoreactive B-cells may be mostly circulating, whereas in patients who do not respond to the same treatment, autoreactive B-cells may chiefly reside into secondary lymphoid organs - and thus be more resistant to the drug action. Researchers will therefore extensively analyze the circulating immune repertoire of MN patients before and after the infusion of B-cell lineage depleting agents, assessing the presence of circulating PLA2R autoreactive B cells from appropriately stratified responder and non-responder patients. Patients and healthy controls will be enrolled in this study. Patients will be stratified according to gender, anti-PLA2R status, type of B-cell lineage depleting agent received and response to treatment.