Using a pool of 18 HLA class I restricted EBV peptides, Jilek and colleagues11 found an increased EBV specific CD8+ T cell response in patients with clinically isolated syndromes but a normal response in established MS whereas another study found that patients with MS had an increased CD4+ T cell response to peptides derived from EBV nuclear antigen-1 (EBNA1).12 This evidence concerns the gene CD4 and myeloid sarcoma.