The study aims to explore the therapeutic value and mechanism of Interleukin-2 on children with Henoch-schönlein purpura.

The investigators designed a single center, open-label, prospective study that routinely administered low-dose IL-2 therapy to monitor the improvement of clinical and laboratory parameters to explore its efficacy and to observe changes in immune cell subsets and cytokines.For all patients,rhIL-2(500,000 unit per square meter) infusions seven days;recurrent patients were applied again for 7 days;patients who were diagnosed HSPN were treated on a routine basis for 7 consecutive days, and then once every two week for 3months.

Inclusion Criteria:

1. age <18 years old
2. meet the EULAR/PRINTO/PRES for the diagnosis of HSP
3. HIV negative;Negative for HBV and HCV.

Exclusion Criteria:

1. heart failure (cardiac function ≥ grade III NYHA)
2. liver insufficiency (upper limit of normal range of transaminase > 2 times)
3. renal insufficiency (creatinine clearance ≤30ml/min)
4. acute or severe infections such as bacteremia and sepsis
5. malignant tumor
6. high-dose steroid pulse therapy or intravenous injection of glucocorticoids in the last 1 month
7. mental disorders or any other chronic illness or substance abuse may interfere with the ability to comply with agreements or provide information
8. Intestinal ischemia or perforated gastrointestinal bleeding requires surgery
9. Inability to comply with IL-2 treatment regimen.