Membranous nephropathy (MN) is a common cause of nephrotic syndrome in adults. It is due, in 80% of  cases, to antibodies against phospholipase A2 receptor (PLAR2), a transmembrane glycoprotein expressed by the human podocyte of the glomerulus, resulting in deposition of subepithelial immunocomplexes.  Nowadays, only anti-PLA2R Ab levels predict treatment response ad outcome in MN patients. When  antibodies are detectable in the patient’s serum, kidneys are already damaged, so it is needed a parameter  that allow the clinician to identify early relapse and to guide the adjustment to therapy. The aim of our  research is to identify specific anti-PLA2R memory B cells as the only trustworthy parameter to recognize relapse before the appearance of antibodies and therefore the kidney damage.