Rituximab in idiopathic nephrotic syndrome: does it make sense?

Idiopathic nephrotic syndrome (INS) includes three different entities: minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), and mesangial proliferative glomerulonephritis. Historically, this condition has been attributed to a T-cell disorder resulting in the secretion of a circulating factor that increases glomerular permeability to plasma proteins. The therapeutic approach to control the proteinuria of INS remains the use of drugs that have been considered to suppress the production of the "circulating factor" secreted by T cells. Recently, rituximab (RTX), a chimeric monoclonal antibody directed against the CD20 cell surface receptor expressed on B cells, has emerged as potential therapeutic agent. The number of publications reporting clinical experience with RTX in the treatment of nephrotic syndrome has greatly increased in the last few years. However, there is currently no good evidence from clinical or experimental studies that support a role of RTX in the treatment of MCD and FSGS proteinuria. In summary, there is the need for a better understanding of the pathogenesis of the proteinuria in INS and the potential role of RTX in this condition.