Interaction between alpha4-integrin and this receptor is an early step in the series of events which allows lymphocytes to migrate from the blood stream into areas of tissue inflammation. Since lymphocyte invasion with secondary brain inflammation and demyelination is thought to be the underlying cause of symptoms in MS, interference with lymphocyte migration may have clinical relevance to treatment of acute exacerbations. Procedure Study participants must first be evaluated for eligibility prior to study enrollment. More than half of participants will receive the study drug. Since the study is blinded, neither the participants nor the treating physician will know the treatment assignment.
Treatment consists of a single intravenous infusion, to be performed in the investigator's clinic.
Participants are asked to return for eight additional visits over a period of 14 weeks for observations and tests including neurological exams and lab tests. Participants are also asked to undergo MRI scans for assessment of MS activity. If a study participant fails to improve after the infusion of study drug or placebo, and if the investigator and participant perceive that treatment is required, the participant will be treated with a standard intravenous course of methylprednisolone. Financial costs for methylprednisolone, above insurance, will be reimburse. Other costs related to study participation, such as travel, parking, meals or temporary lodging, may also be reimbursed, if requested.