Transcriptome of self-reactive proliferating CD19+ B cells in multiple sclerosis

Multiple sclerosis (MS) is a T cell-mediated demyelinating autoimmune disease of the central nervous system causing neurological deficits with substantial disability. Our group demonstrated that self-reactive proliferation of peripheral lymphocytes is increased in MS patients, is associated genetic risk and is involved in the pathogenesis of MS. These observations are based on an established in vitro system, in which peripheral blood mononuclear cells (PBMC) were seeded out for 7 days in serum-free medium in the absence of an exogenous stimulus. In order to track the self-reactive proliferation, cells were labeled with the fluorescent proliferation marker CFSE. We showed that memory CD19+ B cells are enriched in the self-reactive proliferating compartment in RRMS in remission and that these cells are important to interact with and to induce proliferation of brain-homing CD4+ T cells in a HLA-DR-dependent manner.In order to understand the biological relevance of the proliferating cells on a molecular level, we sorted CD19+ B cells from the self-reactive proliferating (gating: singlet+live+CD19+CFSEdim) and non-proliferating (gating: singlet+live+CD19+CFSEhi) compartment by flow cytometry based on CFSE-labeling of PBMCs after stimulus-free co-culture for 7 days. We performed RNA isolation and sequencing of these sorted cell subpopulations from 5 untreated RRMS patients in remission. The data shows expression of CD19+CFSEdim and CD19+CFSEhi cells.