CMV reactivation induces an increase of NKG2C⁺ NK cells and a more mature NK-cell phenotype in the first year after transplantation. NKG2C expression (left panel), mean fluorescence intensity (MFI, right panel, A), CD56^dim expression (B, left top panel), NKG2A expression (B, right top panel), and KIR expression based on a cocktail of Abs against CD158a/h, CD158b/j, and CD158e (B, left bottom panel) and CD57 expression (B, right bottom panel) were measured on CD56⁺ CD3⁻ NK cells from seronegative (○, n = 10), seropositive (no CMV reactivation; ■, n = 5) and seropositive (CMV reactivation; ▵, n = 8) recipients at day 28, day 60, day 100, 6 months, and 1 year after transplantation. Points represent the means ± SEM. The slope of time was compared between recipients who reactivated CMV and combined recipients who did not reactivate CMV using a linear mixed model.