Systemic lupus erythematosus (SLE) is a chronic autoimmune syndrome affecting various organs.Many feel that glucocorticoid and immunosuppressor are the standard therapy for patients with SLE. While it can improve the risk of infection among SLE patients. A novel therapy to treat SLE with low-does IL-2 has been identified recently. IL-2 also used to against some virus infect. So we hypothesized that low-dose IL-2 could reduce risk of infection in SLE patients.