B3GAT1 and Autoimmunity: Our data add to a deeper phenotypic characterisation of these potentially pathogenic CD57+ CD8+ T cells, as well as their CD57+ CD4+ CTL counterparts, thereby providing a robust tool to characterise such disease-specific T cell subsets, and to identify markers that can be used to monitor their frequency using high-throughput methods, such as flow cytometry, in large numbers of autoimmune patients.