HIV-specific CD8⁺ T cells from ECs express higher amounts of T-bet than CPs after proliferation. (A) CFSE-labeled PMBCs from a subset of ECs and CPs were stimulated for 5 days in the presence of a pool of Nef, Gag, or optimal 9-11mer HIV peptides. Representative flow cytometric plots show HIV-specific CD8⁺ T cells, as determined by the production of IFN-γ after restimulation, that have proliferated. Percentages represent the fraction of total CD8⁺ T cells within each gate. (B) The proportion of IFN-γ⁺CFSE^low HIV-specific CD8⁺ T cells positive for perforin, Grz B, and Grz A was determined on day 5 for ECs and CPs. (C-D) T-bet expression was also determined on day 5 after HIV-specific stimulation, with levels reported as the percentage (C) or MFI (D) among IFN-γ⁺CFSE^low HIV-specific CD8⁺ T cells. The reported MFI values indicate the difference between the T-bet^neg population and the T-bet MFI of the IFN-γ⁺CFSE^low cells for each subject. (B-D) Mann-Whitney tests (nonparametric; 2-tailed) were performed to compare ECs with CPs for each functional parameter. **P < .01. Error bars indicate the means and SDs.