Anti-infection of Low-does IL-2 in SLE

Inclusion Criteria: * Meet the American College of Rheumatology criteria for the diagnosis of SLE. * Under standard treatment (≥ 2 months) at the time of inclusion * Background treatment failed to control flares or to permit prednisone tapering * With at least one of the following manifestations: thrombocytopenia, disease-associated rash, mouth ulcer, non-infectious type of fever, active vasculitis, renal disorder(proteinuria\>0.5g/day), neuropsychiatric SLE. * Positive for at least one of the following laboratory tests: ANA\>1:160, anti-dsDNA, immunoglobulin\>20g/L, decreased C3 or C4, leukopenia\<3×10\^9/L, thrombocytopenia\<100×10\^9/L; * SLE disease activity index(SLEDAI) ≥ 8. * Negative HIV test. * Negative for hepatitis B and C virus. * Written informed consent form. Exclusion Criteria: * Sever chronic liver, kidney, lung or heart dysfunction; (heart failure (≥ grade III NYHA), hepatic insufficiency (transaminases\> 3N) ) * Serious infection such as bacteremia, sepsis; * Cancer or history of cancer cured for less than five years (except in situ carcinoma of the cervix or Basocellular carcinoma); * High-dose steroid pulse therapy (\>1.5mg/kg) or IV bolus of corticosteroids in the last 2 months. * History of administration of rituximab or other biologics; * Purified protein derivative (tuberculin) \>10mm * Mental disorder or any other chronic illness or drug-abuse that could interfere with the ability to comply with the protocol or to give information; * Inability to comply with IL-2 treatment regimen.