There are two parts to this investigator sponsored trial (IST):

1. To perform advanced serial MRI studies on patients initiating alemtuzumab therapy.
2. To provide serum samples for the University of Southern California (USC) ICAM125 lymphocyte recovery study.

Multiple Sclerosis (MS) is an inflammatory demyelinating disease of the Central Nervous System (CNS). There are many forms of MS; although the majority are Relapsing Remitting (RRMS) representing approximately 80% of the cases. The disease appears to be more inflammatory in RRMS as manifested by an increase in Gadolinium (Gd) enhancement on MRI and an increase in inflammatory bio-assay markers.

Alemtuzumab; a humanized monoclonal antibody that targets the CD52 molecule present on T and B lymphocytes, natural killer (NK) cells, and monocytes and macrophages; effects rapid and sustained lymphocyte depletion and is approved for the treatment of B-cell chronic lymphocytic leukemia in many countries under the names CAMPATH or MabCAMPATH.

There are two parts to this Investigator Sponsored Trial (IST):

1. To perform advanced serial MRI studies on patients initiating alemtuzumab therapy.
2. To provide serum samples for the University of Southern California (USC) ICAM125 lymphocyte recovery study.

Inclusion Criteria:

• Signed, informed consent form
• Age 18 to 50 years old (inclusive)
• Diagnosis of MS per update of McDonald criteria, and cranial MRI scan demonstrating white matter lesions attributable to MS within 10 years of screening
• Onset of MS symptoms within 15 years of screening
• Neurostatus (EDSS) score 0.0 to 5.0 (inclusive)
• 2 MS attacks (first episode or relapse) occurring in the 24 months prior to screening, with 1 attack in the 12 months prior to screening, with objective neurological signs confirmed by a physician.

Exclusion Criteria:

• Received prior therapy for MS other than corticosteroids within 28 days of screening; e.g., interferon's, IV immunoglobulin, and glatiramer acetate
• Exposure to natalizumab within 6 months of screening
• Any prior exposure to mitoxantrone, mycophenolate mofetil, azathioprine, cladribine, cyclophosphamide, cyclosporine A, methotrexate, rituximab, or any other immunosuppressive agent other than systemic corticosteroid treatment
• Has any progressive form of MS
• History of malignancy (exception for basal cell skin carcinoma)
• Previous hypersensitivity reaction to other immunoglobulin product
• Intolerance of pulsed corticosteroids, especially a history of steroid psychosis
• CD4+, CD8+, or CD19+ (i.e., absolute CD3+CD4+, CD3+CD8+, or CD19+/mm3) count \