Low-dose IL-2 ( Interleukin-2) Treatment in Macrophage Activation Syndrome（MAS）

Inclusion Criteria: * Diagnosis of Macrophage Activation Syndrome（MAS） * MAS secondary to autoimmune disease, such as Adult onset still's disease (AOSD), juvenile rheumatoid arthritis (JRA) or Systemic Lupus Erythematosus (SLE). Exclusion Criteria: * Primary MAS * Secondary to neoplasia, lymphoma and virus infection * pre-treatment with Cyclosporine A * relevant cardiac, pulmonary, neurologic or psychiatric disease * life-Vaccination within 4 weeks before begin with study medication * pregnant or breast-feeding * weight under 45kg or more than 80kg