Amongst the epitopes which activated the MBP85-99-specific T cell clones was a peptide from EBV DNA polymerase (BALF5627-641) in the context of MS-associated alleles HLA-DRB1*15:01 and HLA-DRB5*01:01 respectively, and these clones were subsequently tracked to the cerebrospinal fluid (CSF) of patients and the TCR:peptide-HLA structure solved (137, 138). Here, HLA-DRB1 is linked to myeloid sarcoma.