NK cells expanded ex vivo with aAPCs expressing mbIL21 have higher expression of NKG2D than those expanded with mbIL15. (A) Surface imunophenotyping by flow cytometry was performed on NK cells from each donor after expansion for 3 weeks with the indicated aAPCs. MFI of NKG2D expression is shown for the CD3⁻CD56⁺ population. Four donors in this experiment are representative of over 20 donors tested. P values indicated are for 2-tailed Student paired t test. (B) mRNA was purified from freshly-purified NK cells, or NK cells expanded for 3 weeks as above, and assessed for gene expression copy number of DAP10, DAP12, and NKG2D transcripts on the NanoString platform. Five donors in this experiment are representative of 2 independent experiments. P values indicated are for Student t tests of comparisons to fresh NK cells, with Holm-Sídák correction for multiple comparisons. *P < .05; **P < .01; ***P < .001. NS, no statistical significance.