CXCR1 expression on HIV-1–specific CD8 T cells in noncontrollers and controllers. (A) The percentage of antigen-specific CD8 T cells expressing CXCR1 was assessed by means of HLA class I tetramers combined with antibody staining. The 2 left columns compare CXCR1 expression on HIV-1–specific CD8 T cells in noncontrolling individuals on HAART (shaded column, H5-H11; viral loads below detection limit) with noncontrolling individuals off HAART (nonshaded column, H12-H15; viral load range, 18 000-209 193 copies per mL plasma) (cross-sectional comparison). The 2 right columns longitudinally compare CXCR1 expression on HIV-1–specific CD8 T cells in induced controllers (H1-H4) on HAART (shaded column, viral loads below detection limit) and off HAART (nonshaded column; viral load range, 357-7290 copies per mL plasma). Significant expression of CXCR1 on HIV-1–specific CD8 T cells was observed only in persons on HAART with treated acute HIV-1 infection (induced controllers). (B) Representative flow-cytometry profiles of CXCR1 expression on HIV-1–specific CD8 T cells in noncontrollers and induced controllers, both on and off HAART. (C) In contrast to CXCR1, no significant differences were observed in the percentage of HIV-1–specific CD8 T cells that expressed CCR5, CXCR4, CXCR3, or CX3CR1 when induced controllers were studied on or off HAART. The percentage of HIV-1–specific CD8 T cells that expressed HLA-DR, however, was significantly higher when these were analyzed while people were off, as opposed to on, HAART (60% ± 6% versus 21% ± 6%). Data represent the mean (± SD) of at least 4 independent measurements.