Cord blood contains a low frequency of NK receptor–positive T cells, which can be expanded with common γ-chain cytokines. (A) Cord blood (□) and adult mononuclear cells (▧) were stained for CD3 and 1 of 8 NK/KIR molecules. (B) CBMCs were cultured with IL-2, IL-7, or IL-15, harvested on day 14, and stained for CD3 and 1 of 8 NK/KIR molecules. Cell expansions are expressed as fold increase in the number of cells present after culture, compared with the numbers present before culture. Results are means (± SEMs) of 5 to 9 samples. *P < .01; **P < .005.