Ex vivo enumeration of EBV-specific CD8⁺ T cells using MHC-peptide pentamers in PBMCs from HL patients. The values shown on the logarithmic axis indicate the percentage CD8⁺ T cells positive for HLA class I–peptide pentamers. There was no significant difference in pentamer frequencies between EBV-positive HL and EBV-negative HL cases.