IL-7, IL-15, and IL-2 differ in their capacity to support early and late NK cell differentiation and receptor acquisition.

UCB CD34⁺/Lin⁻/CD38⁻ cells were cultured in direct contact with AFT024 and the indicated cytokines. All results are presented normalized to 10 starting cells. Cultures analyzed at day 25 were started with 25 to 100 sorted cells, and cultures analyzed at day 50 were started with 10 to 25 cells to prevent culture overgrowth. (A) There were significantly greater numbers of NK cells at day 50 with IL-2 compared with IL-15 (P < .001). There was no significant difference between these same cytokines at the early time point. (B) The absolute number of CD56⁺/CD94⁺ NK cells was determined. The absolute number of CD94-expressing NK cells at day 25 was greater for cultures containing IL-15 or IL-2, but by day 50 cultures containing IL-2 contained significantly greater CD56⁺/CD94⁺ NK cells compared with IL-15 (P = .0009). (C) The absolute number of CD56⁺/KIR⁺ NK cells was determined by using a KIR cocktail of antibodies as in Figure 1. The absolute number of KIR-expressing NK cells at day 25 was greater for cultures containing IL-15 or IL-2, but by day 50 cultures containing IL-2 contained significantly greater CD56⁺/KIR⁺ NK cells compared with IL-15 (P = .009). Each condition represents multiple replicates from 3 to 4 donors for each condition.