This study is to evaluate the safety of AMG 623 in subjects with systemic lupus erythematosus. The study consists of a 21 day screening period followed by administration of the investigational product and up to 70 day follow up period.

Inclusion Criteria:

• Men and women, between the ages of 18 and 55
• Diagnosis of SLE
• Have had a disease duration of at least 1 year, as diagnosed by a physician

Exclusion Criteria:

• Have a disorder (including psychiatric), condition or clinically significant disease (other than a diagnosis of SLE) that would interfere with the study evaluation, completion and/or procedures per the investigator's discretion
• Have active vasculitis, active CNS lupus requiring therapy, active acute renal disease, uncontrolled hypertension, uncontrolled diabetes or active systemic infection
• Have had signs or symptoms of viral or bacterial infection within 30 days of enrollment
• Have received a daily dose of greater than 10 mg prednisone (or equivalent) in the prior 30 days