Abstract: Ｏｂｊｅｃｔｉｖｅ：In this study, we investigate the clinical efficacy and safety of ultralow dose Rituximab (RTX) regimen for treatment of lupus nephritis (LN).
Ｍｅｔｈｏｄｏｌｏｇｙ：34 Patients with renal biopsyproven LN were treated with ultralow dose RTX regimen (RTX 100 mg／w×4w followed by RTX 100 mg every 2~3 months for 12 months) in combination with glucocorticoids and immunosuppressive agents. B cell depletion and B cell complete depletion were defined as CD19+cells <5／μL and CD19+cells<1／μL respectively, and B cell reconstruction was defined as CD19+cells≥5／μL. Clinical efficacy and adverse events were retrospectively analyzed within 12 months.
Ｒｅｓｕｌｔｓ：Thirtyfour LN patients including 19 refractory, 8 relapsed and 7 new onset LN were included in this study. Before RTX treatment, 11 patients showed nephrotic syndrome, 8 patients had acute renal injury (AKI) and 7 patients also presented with severe immune cytopenia. In addition to RTX, all patients received immunosuppressant including calcineurin inhibitors (n=30) or mycophenolate mofetil (n=4). After four ultralow dose RTX treatment, 33 patients (971％) achieved B cell complete depletion. 23 (676％) and 18 (529％) patients showed sustained B cell depletion and B cell complete depletion within 12 months of RTX treatment. Totally, 32 patients (941％) achieved remission and 12 (353％) achieved complete remission. No significant difference in remission rates was found among refractory LN (947％), relapsed LN (100％) and new onset LN (857％), but complete remission rate was significantly higher in new onset LN patients than that in refractory LN (714％ vs 214％, P=0024). Renal function was recovered in 7 (875％) patients with AKI on admission. All seven patients accompanied with immune cytopenia achieved normalization of blood cell account. ANA and AntidsDNA tigers turned to negative in 3(88％) and 13 (867％) patients respectively. B cells reconstituted in 11 patients, 2 of whom experienced LN relapse. Infection occurred in 3 patients within the first 3 months, no patient died.
Ｃｏｎｃｌｕｓｉｏｎ：UltraLow dose RTX regimen for lupus nephritis showed a promising efficiency, especially for new onset patients. It is worth carrying out a prospective controlled study of ultralow dose RTX regimen in treatment of LN.

Key words: lupus nephritis, Rituximab, ultra-low dose, B cell depletion