IFN-γ production of the expanded NK cells. Supernatants from 6 × 106 PBMC, D2NK cells cultured for 48 hours at a 6-well plate in 2 ml medium were tested with human IFN-γ EIA kit. The concentrations of IFN-γ from PBMC and D2NK are 154 ± 12 pg/ml, and 5052 ± 493 pg/ml respectively; the culture medium has no detectable human IFN-γ. The PBMC and D2NK from 3 different donors were tested in triplicate for each. The error bars represent SD.