GM-CSF production by human NK cell subsets.

Stimulation with monokines or PMA plus ionomycin induced significantly more GM-CSF protein in cultures of CD56^bright NK cells than in CD56^dim cells (*P < .007; **P < .04; n = 3-7 donors per condition). IL-15 alone induced moderate levels of GM-CSF (751.7 ± 190.4 pg/mL, CD56^bright NK cells), whereas there was no detectable GM-CSF in cultures with IL-12, IL-1β, IL-18, PMA, or ionomycin alone (sensitivity less than 15 pg/mL). ■ indicates CD56^dim; ▪, CD56^bright.