CD8⁺ T cells in D⁺/R⁺ and D⁻/R⁺ HCT recipients expressing each of 4 functional markers. The average percentage of CD8⁺ T cells in samples from D⁺/R⁺ (n = 41) and D⁻/R⁺ (n = 21) HCT recipients (Table 1) that were positive for each of the markers IFN-γ, MIP-1β, CD107, or TNF-α are shown as separate bars. The data bars represent an average of measurements from all 3 time points in all HCT recipients in group 3 (Table 1). Error bars illustrate the range of measurements for each marker.