CD57⁺CD56^dimCD16⁺ NK cells have a higher cytotoxic potential and mediate better CD16-induced cytotoxicity. (A) Percentages of NK cells that express perforin, granzyme B, or both cytotoxic molecules were assessed on CD57⁺CD56^dimCD16⁺ NK cells and CD57⁻CD56^dimCD16⁺ NK cells (● represents CD57⁺; and ◇, CD57⁻). ***P < .0005. P values were determined between CD57⁺ and CD57⁻ NK cells (n = 23). (B-C) Low buoyant density lymphocytes were activated with K562 or 721.221 target cells (B) or with plate-bound antibodies (C) in media with 200 IU/mL IL-2. CD56^dimCD16⁺ NK cells were gated on CD57⁺ and CD57⁻ cells, and the percentages of CD107⁺ cells were determined on each subset (black bars represent CD57⁺; and white bars, CD57⁻). P values were determined between CD57⁺ and CD57⁻ NK cells (n = 8). (D) Sorted CD57⁺ and CD57⁻ CD56^dimCD16⁺ NK cells were activated with P815 target cells coated with anti-CD56 or anti-CD16. *P < .05. P value was determined between the percentage of specific lysis of P815 plus anti-CD16 by CD57⁺ and CD57⁻ NK cells (n = 6, in triplicate).