Markers specifically enriched in CD5+ CD4+ T cells from people with MS compared with NIND included, for example granzyme K, which has been described as a marker for brain-homing, pathogenic Th17.1 cells in neuroinflammation, and an integrin-β chain (IGTB2) also involved in immune cell activation.29–31 On a protein level, CD5 was previously reported to be increased in CSF from people with MS compared with healthy controls, and to be positively correlated with neurofilament light.32 This was in line with our observations in serum in patients outside of relapse activity. Here, NEFL is linked to myeloid sarcoma.