CXCR1 expression on subsets of EBV- and influenza-specific CD8 T cells. The percentage of antigen-specific CD8 T-cell subsets expressing CXCR1 was assessed by means of HLA class I tetramers combined with antibody staining. CD8 T-cell responses were identified by ELISpot analyses using optimal epitope peptides and are given in Figure 5. (A) Percentage of CXCR1 expression on subsets of influenza-specific CD8 T cells. (B) Percentage of CXCR1 expression on subsets of EBV-specific CD8 T cells. Both lytic and latent antigen-specific CD8 T-cell responses were analyzed (Figure 5). (C) Representative flow-cytometry profiles of CXCR1 expression on influenza- and EBV-specific CD8 T-cell subsets.