The idiopathic nephrotic syndrome (i.e. MCNS and FSGS) in children has been regarded as a disorder of T-cell function. Recent studies, however, also describe abnormalities of B-cell function. This supports the use of B-cell modulating treatment for idiopathic nephrotic syndrome (INS), especially rituximab, which has been used in other glomerular disorders as well. Many studies indicate that rituximab is effective in steroid-sensitive and -dependent nephrotic syndrome, by either inducing long-term remission or reducing relapses. In most series, children with primary (and recurrent) focal segmental glomerulosclerosis (FSGS) do not respond as well. The exact mechanisms of action of rituximab (as well as those of the other treatment options) in INS are as yet unclear. In addition to hosting mechanisms a direct stabilizing effect on the podocyte may also be of relevance, especially in FSGS. Although results are encouraging especially in steroid-sensitive patients, further studies on the clinical use of rituximab and the short- and long-term immunological effects and side-effects are necessary.
