Early T-cell reconstitution is associated with the emergence of CMV-induced NKG2C⁺ NK cells in recipients of TCD HCT. (A) NKG2C⁺ cell reconstitution in 3 recipients of TCD HCT who all experienced CMV reactivation by day 30 (gray dotted line) after HCT but exhibited different times of T-cell recovery. (B) Recovery of CD3⁺ T cells and expansion of NKG2C⁺ NK cells at sequential time points after HCT in 3 individuals. Red squares highlight the time point at which T cells were first detected. (C) Percentage of NKG2C⁺ cells among all NK cells (left) and the percentage of patients with NKG2C⁺ NK cell expansions (percentages >4% were considered positive for NKG2C expansion based on non–CMV-reactivated data) at indicated time points relative to T-cell recovery (T0) (right) (n = 16). (D) Percentage of NKG2C⁺ (top) and NKG2A⁺ (bottom) of total NK cells and (E) absolute counts of NKG2C⁺ (top) and NKG2A⁺ (bottom) of CD56⁺CD16⁺ NK cells, relative to time of first T-cell detection (T0) are shown (mean ± SEM) (T1, 447.4 ± 139.6 cells per μL vs T−2, 2.9 ± 0.7 cell per μL; P = .0004). The gradient bar indicates the number of patients with CMV reactivation at the indicated time point. (C-E) T0 is denoted as the time at which T cells were initially detected via flow cytometry in the PB, with T−2 and T−1 as time points before T-cell recovery, and T1 to T3 are time points after T-cell recovery. (D-E) Two-way ANOVA with multiple comparisons was used for statistical analysis. (F) CD3⁺, CD4⁺, and CD8⁺ T-cell absolute counts (CMV reactivation, n = 38; no CMV reactivation, n = 35) (top) and percentages (CMV reactivation, n = 50; no CMV reactivation, n = 60) (bottom) are measured at late time point samples. Interquartile range is depicted by a box with the middle line plotted as the median, and Tukey values are represented by whiskers and outliers. Unpaired/nonparametric t test (CD3) and two-way ANOVA with multiple comparisons (CD4 and CD8) were used for statistical analysis. One-way ANOVA with multiple comparisons was used for statistical analysis. ∗P ≤ .05; ∗∗P ≤ .01; ∗∗∗P ≤ .001; ∗∗∗∗P ≤ .0001.