Figure 4

Functionality of CMV and HIV-specific memory CD4⁺ and CD8⁺ T-cell subsets. The differential expression of CD45RA, CCR7 and CD27 by CD4⁺ and CD8⁺ T-cells was analyzed by boolean gating. Based on the expression of these surface markers we were able to discriminate eight different subpopulations expressing each possible combination of markers: naïve (T_N, CD45RA⁺CCR7⁺CD27⁺), central memory (T_CM, CD45RA⁻CCR7⁺CD27⁺), early and late effector memory (T_{EM early}, CD45RA⁻CCR7^-CD27⁺ and T_{EM late}, CD45RA⁻CCR7⁻CD27⁻), and early and late effector memory re-expressing CD45RA T-cells (T_{EMRA early}, CD45RA⁺CCR7⁻CD27⁺ and T_{EMRA late}, CD45RA⁺CCR7⁻CD27⁻). Other intermediate phenotypes (CD45RA⁺CCR7⁺CD27⁻ and CD45RA⁻CCR7⁺CD27⁻), which can not as yet be ascribed to a specific subpopulation or to a functionally unique subset, observed in low percentages are not shown. The frequency of IFN-γ⁺ and IL-2⁺ CMV and HIV-specific T-cells across distinct subsets are shown. CMV⁺ HIV-uninfected individuals (blue bars, n = 12), CMV⁺ immunoconcordant individuals (green bars, n = 16 and n = 6 for pp65 peptide pool and p24, respectively) and CMV⁺ immunodiscordant individuals (red bars, n = 11 and n = 8 for pp65 peptide pool and p24, respectively). The median and tukey ranges are shown for each group. Differences were tested using Mann-Whitney U nonparametric test (*p < 0.05, **p < 0.01).