This is a multicenter, non-interventional, retrospective cohort study. In MS patients, a recent study suggests that the location of lesions in the brain relative to the ME is associated with different effector T cell responses (Th17 vs. Th1) to myelin proteins. Thus, lesion localization may be associated with different immune profiles.~Recently, high-resolution techniques such as mass cytometry (CyTOF) have allowed to better decipher immune diversity and thus to identify new potential therapeutic targets. The combination of CyTOF and high dimensional analysis techniques (viSNE, SPADE, MEM) offers robust and reliable methods to identify new subgroups within heterogeneous cell populations. Several studies have explored immune subpopulations by these methods, including B, T, NK or myeloid populations, from peripheral blood or tissues in other pathologies.~Genetic analysis of regions of interest in MS patients could thus allow the establishment of stratification elements potentiating the contribution of immunological markers.~The main objective is to evaluate the relevance of an immunological stratification by CyTOF, allowing the identification of new immune subpopulations associated with the lesion phenotype (brain or brain + ME), in a cohort of MS patients at the beginning of the disease (CIS+) The second objective will focus on genomic profiling of our two groups of MS patients (brain/brain + ME) for different genetic burdens of MS
The objective of APOLLO is therefore to identify biomarkers associated with the CNS involvement phenotype in early MS patients.