Age-related changes in NK cell frequencies (A). NK cells were identified within PBMC after gating on singlets and viable lymphocytes. CD56⁺CD3⁻NK cells were then subsequently gated into CD56^bright and CD56^dim subsets. Frequencies of (B) all NK cells, (C) CD56^bright, and (D) CD56^dim NK cells are shown for each age group. Horizontal bars represent median values, boxes extend from the 25th to the 75th percentile, and whiskers represent the 95th percentiles. Asterisks represent significant trends across the entire cohort (*P < .05, ***P < .001, F-test).