The purpose of this study is to determine whether interferon-beta impairs the ability of plasmacytoid dendritic cells to promote pathogenic immune responses in patients with multiple sclerosis.

Inclusion Criteria:

• Males and females, 18 to 60 year old, inclusive.
• Diagnosis of a relapsing form of multiple sclerosis as determined by revised McDonald Criteria or at least one clinical demyelinating episode with abnormal brain MRI study based on CHAMPS criteria
• Expanded disability status scale (EDSS) score less than 6 at entry.
• Understand and sign written informed consent prior to any testing under this protocol, including screening tests and evaluations that are not considered part of the subject's routine care.

Exclusion Criteria:

• Treatment with corticosteroids within one month prior to the study. Treatment with immunomodulatory drugs within last 3 months prior to the study.
• No history of treatment with Interferon-beta(IFN-beta) based drugs to exclude the possibility of IFN-beta neutralizing antibodies
• Any patient who is pregnant, intend to become pregnant, or breastfeeding at any time of the study.
• History of any significant cardiac, gastrointestinal, hepatic, pulmonary, or renal disease; immune deficiency; or other medical conditions that would preclude IFN-beta therapy.
• Primary Progressive Multiple Sclerosis patients or patients with Secondary Progressive Multiple Sclerosis with lack of recent clinical relapses for more than 2 years

Multiple Sclerosis Clinic patient