Altered NK-cell homeostasis in a subset of patients with neutropenia. (A) Study design. (B-C) Flow cytometry analysis of frequencies of CD56^bright/dim among total NK cells. A subset of 14 patients with neutropenia (NP) with elevated levels of CD56^bright cells (defined as >HD mean +3 standard deviations, were relabeled NK^imm. (D) Frequencies of CD56^bright cells in NK^imm patients sampled 2 years apart. (E) Frequency of total CD56⁺ NK among PBMCs. (F) Cell counts of CD56⁺ NK cells. (G-H) Subset level phenotyping of CD56^dim NK cells based on NKG2A, KIR, and CD57 expression. (I) The frequency of CMV⁺ donors with an adaptive NK-cell population (aNK) within each group. HD (n = 20), NP (n = 39), and NK^imm (n = 14). *P < .05; **P < .01; ***P <.001; ****P < .001 by nonparametric test, and binomial distribution (I).