Dysfunction of regulatory T (Treg) cells has been detected in diverse autoimmune diseases, which can be promoted by interleukin-2 (IL-2). In a previous small sample trail performed by the investigator's group, the investigators found that the Low-dose IL-2 was effective and well tolerated in active SLE, and the effect was associated with selective modulation of CD4+ T cell subsets.

This clinical study will confirm the efficacy and safety of low dose IL-2 treatment in SLE.

The investigators perform a single-centre, double-blind pilot trial with hrIL-2 in SLE.The investigators evaluate the effectiveness and safeness of low-dose hrIL-2 for Systemic lupus erythematosus by randomized controlled study (hrIL-2 (N = 30) versus placebo group (N = 30)).

Each SLE patients (n=60) with Scores>=8 on SLEDAI received low-dose IL-2 or placebo (active group: placebo group =1:1, 1 million units every other day subcutaneously (HrIL-2 1X 106, ip, Qod) for a period of 14 days. After a 14-day rest, another cycle started) for 3 cycles. The end points were safety and clinical and immunologic response.

Inclusion Criteria:

• Meet the American College of Rheumatology criteria for the diagnosis of SLE，1997.
• 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.
• Negative urine pregnancy test.
• 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.