Expanding NKG2C⁺ NK cells are more mature (KIR⁺ and NKG2A⁻) in the first year after CMV reactivation. NKG2C⁺ NK cells from seronegative (top panel), seropositive (no CMV reactivation, middle panel), and seropositive (CMV reactivation, bottom panel) recipients at the indicated time points were gated as being either NKG2A⁺ (○) or NKG2A⁻ (■, A) and either KIR⁺ (○) or KIR⁻ (■, B) based on a cocktail of Abs against CD158a/h, CD158b/j, and CD158e. Points represent the means ± SEM. NKG2A⁺ and NKG2A⁻ NK cells (or KIR⁺ and KIR⁻ NK cells) were compared for the same group of recipients at each time point using the paired t test. *P ≤ .05 and **P < .01.