The project entitled:”Role of the bone marrow in the maintenance of pathogenic or protective CD4+T-cell subsets in multiple sclerosis” has 3 objectives: i. to monitor EOMES+Tr1-cells, as well as conventional FOXP3+Tregs and cytotoxic CD4+ effector T-cells, in the cerebrospinal fluid (CSF) and the blood of MS, SH and AD patients by multi-parametric flow cytometry to establish if they are enriched and/or activated in the CSF. ii. to investigate if myelin-derived self-antigens or disease-associated viral antigens activate regulatory and/or cytotoxic effector cells to understand if the cells are involved in the disease or rather represent irrelevant bystander cells. iii. to generate and/or analyse single cell RNA and TCR sequencing data in the CSF to identify cytotoxic and regulatory T-cell clusters by bioinformatic analysis in an unbiased manner.