EBV-driven in vitro proliferation of NKG2A⁺ KIR^- NK cells partially depends on expression of lytic antigens. Proliferation of NK-cell subsets was assessed 7 days after inoculation of CBMCs with either WT EBV, BZLF1-KO (BZ1KO) EBV or PBS (MOCK). (A) Concentrations of IFN-α in supernatant 24-hour postinoculation on MOCK, WT EBV, and BZ1KO EBV infection (pg/mL; n = 5). (B) Representative example of CD19 and GFP costaining within live lymphocytes 72 hours postinfection. Numbers indicate frequencies of GFP-negative or GFP-positive cells within the CD19⁺ B-cell population. (C) Frequencies of Ki-67⁺ NKG2A⁺ KIR⁻ NK cells 7 days after inoculation of CBMCs with mock, WT EBV, or BZ1KO EBV, or after stimulation with IL-2. The depicted gates were assessed within live lymphocytes (first row), CD3⁻ CD56⁺ NK cells (second row), and NKG2A⁺ KIR⁻ NK cells (third row). (D) Ratio of NKG2A⁺ KIR⁻ Ki-67⁺ NK-cell counts from WT EBV- or BZ1KO EBV- over mock-infected CBMCs. (E) Frequencies of CD56^dim NKG2A⁺ KIR⁻ NK cells in newborns (n = 8), children aged 1 to 5 years (n = 16), children aged 5 to 15 years (n = 17), and adults aged 20 to 30 years (n = 15). (F) Counts of CD56^dim NKG2A⁺ KIR^- NK cells in children aged 1 to 5 years (n = 14), children aged 5 to 15 years (n = 15), and adults aged 20 to 30 years (n = 15). Horizontal lines indicate median values of a given age group, Mann-Whitney U tests.