The trial will study 2 doses of Immune Globulin Intravenous (Human), 10% Caprylate/Chromatography Purified (IGIV-C) for the number of relapses that occur in a 1 year treatment period.

This trial is designed as a multi-national, randomized, double-blind, placebo-controlled prospective trial with three parallel groups.

One hundred twenty (120) patients, 40 per treatment arm, with relapsing-remitting (RR) multiple sclerosis will be enrolled in this trial. Eligible patients must have a diagnosis of MS as per the McDonald Criteria. In addition, patients must have a diagnosis of relapsing-remitting course of MS defined as periods of worsening of neurological function with full recovery or with sequelae and residual deficit upon recovery; periods between disease relapses characterized by lack of disease progression. Patients must also have active disease with at least 1 defined documented relapse in the last year.

During a 2 month run-in period, 2 MRIs will be performed 6 weeks apart and patients will be stratified based on the presence or absence of 1 or more Gadolinium enhancing lesions on the first MRI (Gd-enhancing lesion yes-no) and will be randomized to one of two dose regimens of IGIV-C or matching placebo. Patients will receive study drug infusions every 4 weeks for 48 weeks for a total of 12 infusions. Patients will be evaluated by MRI every 6 weeks and by clinical assessments every 3 months. A follow-up visit will occur 4 weeks after the last infusion.

The treatment groups are as follows:

• IGIV-C - 0.2 g/kg body weight (bw)/infusion (2 ml/kg bw)
• IGIV-C - 0.4 g/kg bw/infusion (4 ml/kg bw)
• placebo (0.1% albumin) - 4 ml/kg bw/infusion

For blinding purposes, at each infusion, all patients will receive a total volume of 4 ml/kg bw. For patients receiving 0.2 g/kg bw of IGIV-C, the final volume of 4 ml/kg bw will be adjusted by the addition of dextrose 5%. Placebo will be supplied as Albumin 5% or Albumin 25% and diluted with either dextrose 5% or saline to a final concentration of 0.1% albumin.

Dose adaptation will be performed for subsequent infusions in case the patient's body weight has changed > 10%. The maximum amount available per infusion will be 400 ml (8 vials) calculated for a patient with a body weight of 100 kg. The suggested initial infusion rate will be 0.02 ml/kg/min for the first 15 minutes. If there is no evidence of a hypersensitivity reaction, the infusion may be given at a slowly increasing rate over the next 30 minutes up to a maximum allowable rate of 0.08 ml/kg/min. As such, the infusion for a 70 kg patient will take approximately 1hour 15 min. The overall infusion time may have a range from 1 to 2 hours.

Inclusion Criteria:

• Symptoms consistent with Multiple Sclerosis up to 5 years
• Diagnosis of multiple sclerosis according to McDonald criteria.
• Diagnosis of relapsing-remitting (RR) multiple sclerosis (MS) (Defined as periods of worsening of neurological function with full recovery or with sequelae and residual deficit upon recovery; periods between disease relapses characterized by lack of disease progression
• Kurtzke Extended Disability Status Scale (EDSS) < 5.0
• At least 1 defined and documented relapse during the last year. Prior relapses where symptoms were due solely to a change in Bowel/Bladder Function or Cognitive Function will not be considered relapses as defined by this protocol and therefore not counted for inclusion into the study.
• Females or males; females of childbearing potential must use adequate contraception
• Clinically stable for at least 30 days prior to entry
• At least 9 hyperintense T2 lesions on MRI or 1 Gd-enhancing lesion according to McDonald/Barkhof dissemination-in-space criteria at entry
• Patients who have been informed about available treatments and decided, not to go on these treatments
• Written informed consent obtained prior to the initiation of any study related procedures

Exclusion Criteria:

• Females who are pregnant, breast feeding, or if, of childbearing potential, unwilling to practice adequate contraception throughout the study
• Prior therapy with azathioprine or any immunosuppressant agents within 6 months prior to study entry
• Prior steroid, methylprednisolone or adrenocorticotropic hormone (ACTH) therapy within 30 days prior to study entry
• Therapy with interferons (Betaseron®, Avonex®, Rebif®), glatiramer acetate (Copaxone®) or IGIV within 3 months prior to study entry or during the study
• Use of an investigational compound within 6 months prior to study entry
• Previous lymphoid irradiation or prior to treatment with cyclophosphamide, methotrexate or mitoxantrone
• Cardiac insufficiency (NYHA III/IV), cardiomyopathy, significant cardiac dysrhythmia requiring treatment, unstable or advanced ischemic heart disease (CCS III or IV), or malignant hypertension
• History of renal insufficiency or serum creatinine levels greater than 2.5 mg/dL (221 µmol/L)
• Known selective immunoglobulin A (IgA) deficiency or known antibodies to IgA
• Conditions whose symptoms and effects could alter protein catabolism and/or immunoglobulin G (IgG) utilization (e.g., protein-losing enteropathies, nephrotic syndrome)
• Any medical, psychiatric or other circumstances which impede or restrict the patient's participation in the study or any contraindication to contrast enhanced MRI (e.g.,pacemaker, aortic clip or any metal implant)
• Patients with clinically significant medical conditions including, but not limited to cardiac, pulmonary, hepatic, hematological (e.g. known coagulation disorder, history of deep venous thrombosis and/or pulmonary embolism), endocrine,or renal dysfunction, autoimmune disorders, severe environmental allergies or chronic infections