TF expression in CD8 T cells during HIV and CMV chronic infections. (A) Chr-tet⁺ cells were subdivided according to their CD27/CD28 phenotype; and in each patient, 60 cells from each population were studied to determine the expression frequencies of the different TF. Results are the mean ± SD of 9 donors. Data from the outlier MM30 are not included in this figure. Data from HIV-seronegative subjects shown in Figure 1 are included in gray to facilitate comparison. Differences between HIV-seronegative and infected donors: 27SP: Tbx21, P < .0006; Eomes, P < .02; Prdm1, P < .05; DN: Tbx21, P < .0006; Prdm1, P < .05. (B) Expression of TF in DN tet⁺ CMV-specific cells from seronegative donors, identified by labeling with MHC class I tetramers loaded with CMV peptides. In each subject, 60 individual cells were used for frequency analysis. Results are the mean ± SD in 4 subjects. We could only study CMV-specific DN cells because the majority of CMV-specific CD8 T cells have the DN phenotype,^23,24  and we could not recover sufficient numbers of CMV-specific cells with other phenotypes for efficient analysis. Frequency estimates in CMV-specific DN CD8s were not significantly different from those of the DN populations from seronegative donors.