Inclusion Criteria

Inclusion Criteria

1. Signed, informed consent form (ICF)

2. Age 18 to 50 years old (inclusive) as of signing the ICF

3. Diagnosis of MS per update of McDonald criteria, and cranial MRI scan demonstrating
white matter lesions attributable to MS within 10 years of screening

4. Onset of MS symptoms (as determined by a neurologist) within 15 years of screening

5. EDSS score 0.0 to 5.0 (inclusive)

6. >=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

7. Subjects previously enrolled and randomized to interferon beta 1a in the CARE-MS 323
and 324 studies, and who will be treated with Alemtuzumab through the CARE-MS
extension study will be eligible to participate in the immunology and MRI studies of
this protocol.

Exclusion Criteria

1. Received prior therapy for MS other than corticosteroids within 28 days of screening;
e.g., interferons, IV immunoglobulin, and glatiramer acetate

2. Exposure to natalizumab within 6 months of screening

3. Any prior exposure to mitoxantrone, mycophenolate mofetil, azathioprine, cladribine,
cyclophosphamide, cyclosporine A, methotrexate, rituximab, or any other
immunosuppressive agent other than systemic corticosteroid treatment

4. Has any progressive form of MS

5. History of malignancy (exception for basal cell skin carcinoma)

6. Previous hypersensitivity reaction to other immunoglobulin product

7. Intolerance of pulsed corticosteroids, especially a history of steroid psychosis

8. CD4+, CD8+, or CD19+ (i.e., absolute CD3+CD4+, CD3+CD8+, or CD19+/mm3) count Screening; if abnormal cell count(s) return to within normal limits, eligibility may
be reassessed

9. Seropositivity for human immunodeficiency virus (HIV)

10. Significant autoimmune disease (e.g, immune cytopenias, rheumatoid arthritis,
systemic lupus erythematosus, other connective tissue disorders; vasculitis;
inflammatory bowel disease; severe psoriasis)

11. Presence of anti-thyroid stimulating hormone (TSH) receptor (TSHR) antibodies

12. Active infection, e.g, deep-tissue infection, that the Investigator considers
sufficiently serious to preclude study participation

13. Latent tuberculosis unless effective anti-tuberculosis therapy has been completed, or
active tuberculosis. Patients will be assessed for this risk based on a screening
questionnaire.

14. Infection with hepatitis B virus or hepatitis C virus

15. Of childbearing potential with a positive serum pregnancy test

16. Unwilling to agree to use a reliable and acceptable contraceptive method throughout
the study period

17. Major psychiatric disorder that is not adequately controlled by treatment

18. Epileptic seizures that are not adequately controlled by treatment

19. Major systemic disease or other illness that would, in the opinion of the
Investigator, compromise patient safety or interfere with the interpretation of study
results

20. Medical, psychiatric, cognitive, or other conditions that, in the Investigator's
opinion, compromise the patient's ability to understand the patient information, to
give informed consent, to comply with the trial protocol, or to complete the study

21. Confirmed platelet count < the lower limit of normal (LLN) of the evaluating
laboratory at Screening or documented at <100,000/uL within the past year on a sample
without clumping

22. Prior history of invasive fungal infections

23. Cervical high risk human papillomavirus (HPV) positivity or abnormal cervical
cytology other than abnormal squamous cells of undetermined significance (ASCUS).
The patient may be eligible after the condition has been effectively treated (eg,
follow-up HPV test is negative or cervical abnormality has been treated).

24. Seropositive for Trypanosoma cruzi or the Human T-lymphotropic virus type I or type
II (HTLV-I/II) (testing required in endemic regions only)

25. Any other illness or infection (latent or active) that, in the Investigator's
opinion, could be exacerbated by alemtuzumab treatment

26. Any hepatic or renal function value grade 2 or higher at Screening, with the
exception of hyperbilirubinemia due to Gilbert's syndrome. See Table below, drawn
from the National Cancer Institute (NCI) Common Terminology Criteria for Adverse
Events v3.0 (CTCAE), published 09 August 2006