CD56^bright cells produce abundant IFN-γ and GM-CSF transcript.

NK cell subsets were activated for 24 hours with the indicated monokines, and RNA was harvested. Resultant cDNA was analyzed for IFN-γ and GM-CSF transcripts by real-time PCR. Results represent fold-increase in cytokine transcript compared to resting NK cell subsets ± SEM and are representative of 3 experiments. (A) CD56^bright NK produced high levels of IFN-γ transcript in response to IL-12 plus IL-1β, IL-15, and IL-18 compared to the CD56^dim subset. (B) CD56^bright NK cells also produced more GM-CSF transcript in response to monokine stimulation, including activation with IL-15 alone. All results were calibrated to an internal control (18s ribosomal RNA) to normalize for differences in total cDNA. ■ indicates CD56^dim; ▪, CD56^bright.