The etiologic mechanisms involved in multiple sclerosis (MS) are not yet fully understood. Indeed MS is a multifactorial disease involving genetic and environmental factors and Epstein-Barr-Virus (EBV) could be one of these factors. However the link between EBV infection and the immunological mechanisms underlying MS is not clear. Robust sero-epidemiological evidences support an association between EBV infection and MS, and immunological data suggest an altered/deficient immune response against this virus. In healthy individuals EBV produces a persistent infection that is tightly controlled by the immune system. In patients with MS, cellular and humoral immune studies demonstrate an altered response against the virus with a T-cell abnormal reactivity against the EBV-infected autologous B-cells, elevated humoral immune response to Epstein Barr Nuclear Antigen-1, and in the case of children, an increased EBV shedding, demonstrating frequent EBV reactivations. Thus, it has been proposed, that patients with MS present a partially inefficient control of the EBV infection. Some experimental data support the hypothesis suggesting that the presence of autoreactive EBV-B cells in the meninges of patients, probably due to an insufficient clearance of these cells by the immune system, lead to the infiltration of autoreactive T cells. Another hypothesis also suggests a deficient control of the virus, in that case during the inactive phase of the disease. Together, the above data and hypotheses lead to the notion that an immune intervention capable of restoring the host-EBV balance could be beneficial to MS patients In this project, we will assess the feasibility and safety of autologous transfer of several amounts of CD8 T cells directed against autologous EBV transformed B cell lines, in order to finally restore an efficient control of EBV in MS patients. The main objective of the project is to test the feasibility and safety of the process, while efficacy parameters will be also assessed in secondary objectives.