Relapse of nephrotic syndrome during B-cell depletion after single dose of rituximab

We investigated the clinical character of relapses of nephrotic syndrome during B-cell depletion in 137 patients with refractory steroid-dependent nephrotic syndrome who received 375 mg/m 2 of single dose of rituximab. In 440 rituximab treatment, relapses during B-cell deletion were observed 25 times in 19 patients (5.7%). Forty-four percent of them were observed within 14 days after treatment of rituximab. Gender, age of onset of nephrotic syndrome, age at rituximab treatment, renal histology, past histories of steroid resistance showed no difference between patients who relapsed during B-cell depletion and others. Infusion reaction also was not calculated as a risk factor. Two third of patients who relapsed during B-cell depletion could discontinue steroid during B-cell depletion, which showed effectiveness of rituximab. According to the result of this study, we believe that we should maintain doses of steroid as relapse-preventable doses until two weeks after rituximab treatment. Even if patients suffered from relapse during B-cell depletion, rituximab might be effective and their disease character might be pathogenetically same as others. As we could not detect risk factors of relapse during B-cell depletion, prediction is difficult.