CXCR1 expression on effector subsets in human peripheral CD8⁺ T cells. (A) Differential expression of perforin and CXCR1 on/in CD27⁻CD28⁻CD45RA^+/− subsets of human CD8⁺ T cells in freshly isolated PBMCs is shown as 1 representative result from 4 healthy individuals. The values in each plot show the frequency of each population. (B) Gene-expression profiles of CXCR1⁺ and CXCR1⁻ cells in the CD27⁻CD28⁻ effector subset, the CD27^highCD28⁺CD45RA⁺ naive subset, and the CD27⁺CD28⁺CD45RA⁻ memory subset are shown as the mean relative gene-expression levels and SD from 4 healthy individuals. (C) HCMV-1-A*0201 tetramer⁺ cells among PBMCs from a HCMV-seropositive healthy individual (U-14) were analyzed for their CXCR1 expression. The percentage of CXCR1⁺ cells in each CD27CD28 subset of tetramer-positive cells was also determined. (D) Cytolytic activities of CXCR1⁺ and CXCR1⁻ cells in the effector subset toward C1R-A*0201 cells prepulsed with the HCMV-1 pp65 ^495-503 peptide.