Antigen-specific stimulation of HIV-1– and EBV-specific CD8 T cells in vitro. PBMCs from study subjects H1, H3, H4 (all HIV-1), and E3 (EBV) were pulsed with antigen (HIV-1 or EBV peptide) or control peptide (c-peptide) or were left unpulsed (no peptide). After a 4-hour incubation, expression of CXCR3 (A), CX3CR1 (B), and CXCR1 (C-D) was assessed on antigen-specific EMRA CD8 T cells. Note that CXCR3 cell-surface expression increased, while CX3CR1 levels did not change following the 4-hour incubation, irrespective of incubation conditions. In contrast, CXCR1 expression decreased on HIV-1– and EBV-specific EMRA CD8 T cells stimulated with cognate antigen. Data represent the mean (± SD) of 3 and 2 independent experiments for HIV-1 and EBV, respectively.