The study aims at identifying the type of B and CD4 T cell subsets with pathogenic properties in the different clinical forms of multiple sclerosis. This research might open new therapeutic approaches for the treatment of multiple sclerosis particularly progressive MS.

Multiple sclerosis (MS) is a chronic autoimmune disease damaging the central nervous system (CNS). MS is categorized into several distinct forms according to clinical symptoms and medical examinations. Relapsing-remitting multiple sclerosis (RRMS) is characterized by attacks of worsening neurologic function, followed by partial or complete recovery periods. Patients can also present a gradual but steady progression of the disease (progressive forms). While several treatment options are currently available, no treatment completely stops the disease progression. Therefore, a deeper understanding regarding the mechanism of the disease development is essential to generate more efficient treatment strategies. CD4 T cells are known to be significantly involved in the formation of the CNS lesions characteristic of MS.The investigators hypothesize that different types of B and CD4 T cells play major roles in different forms of the disease. They will determine the phenotype and functions of the cells from the immune system particularly B and CD4 T cells present in the blood and cerebro-spinal fluid (CSF) of patients diagnosed with multiple sclerosis or presenting a clinically isolated syndrome.

The study will recruit 150 patients followed in Bordeaux University Hospital and diagnosed for clinically isolated syndrome (CIS) or multiple sclerosis (MS). Blood and CSF will be collected during a scheduled visit to study the properties of cells from the immune system in particular CD4 T cells in multiple sclerosis. Clinical and biological disease activity, treatment and outcomes will be studied in correlation with the properties of blood and CSF lymphocytes. No extra visit will be needed and the blood and CSF samples will be collected at the same times as those collected for clinical purposes.

Inclusion Criteria:

• male or female subjects ;
• Age ≥ 18 years;
• subjects with MS defined by 2010 revised McDonald criteria or presenting a clinical isolated syndrome;
• patients for which a blood draw and / or lumbar puncture to collect CSF is performed for diagnostic or therapeutic purpose;
• affiliated to an health insurance system;
• and who agree to participate in the study.

Exclusion Criteria:

• Pregnant or breastfeeding women,
• patient concerned by articles L 1121-5 to L 1121-8 (persons deprived of their liberty by a judicial or administrative decision, minors, persons of legal age who are the object of a legal protection measure or unable to express their consent)