This study is performed to evaluate the efficacy and safety of various measures in the treatment of severe HSP in children.

Henoch-Schonlein purpura (HSP) is a systemic vasculitis affecting small vessels with immunoglobulin A (IgA)-dominant immune deposits. The clinical manifestations of severe HSP vary from massive hemorrhage and necrosis of the skin to severe gastrointestinal symptoms. The course of the disease would encounter delay and relapse. To some extent, the traditional therapy alleviate the clinical symptoms, but fail to timely clear up the immune depositions, causing the damage to the kidney.

In the study, the patients will be given dexamethasone 0.5mg/kg/d, then be randomised to receive either gamma globulin i.v. or hemoperfusion if the disease can't be controlled with steroid treatment for more than two days.

The investigators will explore the biological markers and compare the efficacy and safety of both measures in the treatment of serve HSP in children. The purpose of the study is to optimize the treatment of severe HSP for children with different ages.

Inclusion Criteria:

• Severe HSP: could not be controlled with dexamethasone 0.5mg/kg/d or the total dose above 20mg/d for more than two days

Exclusion Criteria:

• The children with congenital diseases