Reactivity of KK10-specific CD8⁺ T-cell populations to emerging L₂₆₈M mutants. (A) Ag sensitivity of KK10-specific CD8⁺ T-cell populations from 4 HLA-B*2705⁺ individuals infected with HIV-1 was measured directly ex vivo using IFN-γ ELISPOT analysis across a range of wt KK10 and mutant L₂₆₈M peptide concentrations. The patients harbored predominantly either wt (02.011) or L₂₆₈M (11.007, 01.225, and 05.005) viruses at the time point studied. (B) SFC ratio of wt/L₂₆₈M-specific responses are plotted for each patient. Ratios were calculated for each peptide concentration and are shown as the mean ± SEM for all peptide concentrations. (C) Ag sensitivity (EC₅₀ values) for the wt KK10 and mutant L₂₆₈M peptides in each individual. SFC indicates spot-forming cell.