Inclusion Criteria:
* Diagnosis of SLE per current ACR classification criteria
* Date of SLE diagnosis within 2 years of screening
* ANA positive (with a titer ≥ 80)
* anti-ds DNA antibody positive
* Mild to moderate disease activity define by a SLEDAI-2K ≥4
* Stable corticosteroid dose in the 4 weeks prior to screening ≤ 30mg/day.
* If on methotrexate, dose must be stable for 4 weeks
* Concomitant treatment with hydroxychloroquine unless documented inability to tolerate
* Able and willing to give written informed consent and comply with the requirements of the study protocol
* Negative serum pregnancy test (for women of child bearing potential)
* Men and women of reproductive potential must agree to use an acceptable method of birth control during treatment and for 16 weeks after completion of treatment
Exclusion Criteria:
* Previous exposure to disease modifying drugs such as azathioprine, mycophenolate mofetil, cyclophosphamide, or cyclosporine.
* Previous exposure to biologic therapies including rituximab, belimumab or other agents that have been investigated for SLE.
* Active renal or nervous system disease or disease activity fulfilling BILAG A criteria
* Use of high dose steroids (\>0.5 mg/kg/ day) within the 4 weeks prior to screening
* Expectation (by the investigator) that the subject will require treatment with a disease modifying drug within the first 52 weeks of the study
* Hemoglobin: \< 8.0 gm/dL
* Platelets: \< 50,000/mm
* ANC \< 1.0 x 103/mm
* AST or ALT \>2.5 x Upper Limit of Normal unless related to primary disease.
* Creatinine clearance ≤ 25ml/min per 1.73 m2
* Positive Hepatitis B or C serology (Hep B Surface antigen, Hep B core Ab or Hepatitis C antibody)
* History of positive HIV (HIV conducted during screening if applicable)
* Treatment with any investigational agent within 4 weeks of screening or 5 half-lives of the investigational drug (whichever is longer)
* Receipt of a live vaccine within 30 days prior to baseline or concurrently with belimumab
* Have a history of an anaphylactic reaction to parenteral administration of contrast agents, human or murine proteins or monoclonal antibodies
* Currently on any suppressive therapy for a chronic infection (such as tuberculosis, pneumocystis, cytomegalovirus, herpes simplex virus, herpes zoster and atypical mycobacteria)
* Hospitalization for treatment of infection within 60 days of Day 0.
* Use of parenteral (IV or IM) antibiotics (antibacterials, antivirals, anti-fungals, or anti parasitic agents) within 60 days of Day 0
* History of serious recurrent or chronic infection
* Lack of peripheral venous access
* History of drug, alcohol, or chemical abuse within 365 days prior to Day 0
* Pregnancy (a negative serum pregnancy test must be obtained for all women of childbearing potential at screening; a urine pregnancy test must be negative \< 7 days prior to first dose and monthly)
* Lactation
* History of psychiatric disorder that would interfere with normal participation in this protocol
* Significant cardiac or pulmonary disease (including obstructive pulmonary disease)
* Any other disease, metabolic dysfunction, physical examination finding, or clinical laboratory finding giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or render the patient at high risk from treatment complications
* History of malignant neoplasm within the last 5 years with the exception of adequately treated basal or squamous cell carcinoma of the skin or carcinoma in situ of the cervix
* Evidence of serious suicide risk including any history of suicidal behaviour in the last 6 months and/or any suicidal ideation in the last 2 months or who in the investigator's judgment, pose a significant suicide risk
* History of a primary immunodeficiency
* Have a significant IgG deficiency (IgG level \< 400 mg/dL)
* Have an IgA deficiency (IgA level \< 10 mg/dL)
* Have any other clinically significant abnormal laboratory value in the opinion of the investigator
* Comorbidities requiring corticosteroid therapy, including those which have required two or more courses of systemic courses of systemic corticosteroids within the previous 12 months
* Inability to comply with study and follow-up procedures
