Expanded NK cells display distinct phenotypic and functional properties. (A) Representative staining of the indicated surface molecules on NK cell expansions in the NKG2C⁺ and NKG2C^-NKG2A^- NK cell subsets from CMV-seropositive donors. (B) Aggregated phenotypes of 10 representative NKG2C⁺ expansions compared with the 18 identified NKG2C^-NKG2A^- outliers with (n = 8) and without (n = 10) a differentiated phenotype. (C) NK cells were stimulated overnight with IL-12 and IL-18 in the presence of brefeldin A and were stained intracellularly for IFN-γ production. The figure shows IFN-γ production in NK cell expansions originating from NKG2C⁺ (n = 10) and NKG2C^-NKG2A^- (n = 8) compartments. (D) NK cells were stimulated for 2 hours with rituximab-coated Raji cells in ADCC experiments and were stained for CD107a to monitor degranulation. The figure shows CD107a expression in NK cell expansions originating from NKG2C⁺ (n = 10) and NKG2C^-NKG2A^- (n = 8) compartments. In (B-D), all comparisons were made with the relevant KIR⁺ NK cell subset.