HDC and stroma induce CD34⁺CD38⁻NKlin⁻ progenitors to become NK cells. (A-B) CD34⁺CD38⁻NKlin⁻ cells were cultured at 100 cells/well in 12 replicates. After (A) 14 and (B) 21 days one-half the contents of each well were harvested and analyzed for the presence of CD56⁺ cells by FACS (enumeration was performed with polystyrene beads). The average number of CD56⁺ cells/well is presented. A representative donor is shown (n = 4). Groups showing significant differences are indicated by asterisks (***P < .001, **P = .001-.01, and *P = .01-.05), 1-way analysis of variance on log-transformed values with Bonferroni posttest. (C) Phenotype of cells derived from CD34⁺CD38⁻NKlin⁻ cells less than various conditions. Representative examples of individual wells after 14 days of culture with cytokines alone (IL-15, IL-7, SCF, FLT-3L, and IL-3; left), cytokines and HDC (second column), cytokines and stroma (third column), and cytokines and HDC and stroma (right).