A Study to Compare the Efficacy and Safety of Tacrolimus Capsules With Leflunomide Tablets in Lupus Nephritis Patients

Inclusion Criteria: * body weight 40-100kg * diagnosed as systemic lupus erythematosus, (according to American College of Rheumatology Diagnostic Criteria,1997) * diagnosed as type III/ IV of lupus nephritis by renal biopsy within 6 months * 24hr proteinuria ≥2g and/or active urinary sediments Exclusion Criteria: * receiving immunosuppressant * receiving routine treatment of tacrolimus and leflunomide within 1 month * receiving nonsteroidal anti-inflammatory drugs (NSAIDs) within 1 months before the study * history of allergy to tacrolimus and leflunomide * anticipated maintenance dialysis persisted over 8 weeks; or already being dialyzed over 2 weeks before recruitment * planning to receive kidney transplantation or in the near future or having a history of undergoing kidney transplantation * serum creatinine (Scr) ≥3mg/dl or estimated glomerular filtration rate (eGFR) \< 30ml/min * diabetes mellitus patients