Study to Assess the Efficacy and Safety of FK506 Combined With Mycophenolate Mofetil (MMF) in Lupus Nephritis (III/IV/V)

Inclusion Criteria: 1. Female patients with a diagnosis of systemic lupus erythematosus (SLE) according to the criteria of American Rheumatic Association, 1982, aged between 12-50 years, with score of SLE-DAI (Disease Active Index) of more than 12 (not including class V LN). 2. Patients diagnosed according to ISN/RPS 2003 classification criteria: class Ⅲ, Ⅳ, Ⅳ + Ⅴ, Ⅲ + Ⅴ LN by renal biopsy within 3 months, CI\< 4，Scr\< 3 mg/dl. 3. Patients with a proteinuria ≥ 1.5 g/24h, or active urine sediment. 4. Patients who signed written informed consent forms (patients less than 18 years old with their parents/legal representative' signatures), and have given their consent to follow all study procedures and follow-ups. Exclusion Criteria: 1. Patients who have received treatment of cytotoxic drugs such as cyclophosphamide (CTX), cyclosporine A for more than 1 week within three months. 2. Patients with serum creatinine ≥ 3 mg/dl（265 μmol/L). 3. Patients with severe infection or central nervous system symptoms. 4. Patients who have impaired liver function, with ALT/GPT or AST/GOT twice more than the normal upper limit or who have active hepatitis. 5. Patients who have abnormal blood glucose, with a fasting blood glucose \> 6.2 mmol/L or post meal blood glucose \> 11.2 mmol/L. 6. Patients who are pregnant or lactating. 7. Patients who are known to be allergic to a macrolide.