Figure 1.

PSK stimulates IFN-γ production from CD56^bright NK cells. (A) Dose-dependent induction of IFN-γ secretion by PSK. Shown are IFN-γ concentrations (mean±SD) in culture supernatant from duplicate culture wells of PBMC stimulated with different concentrations of PSK for 24 hours. Similar results were obtained from three different donors. (B) Representative dot plots showing the gating of CD56^dim and CD56^bright NK cells and IFN-γ production in PBS control or PSK-stimulated CD56^dim or CD56^bright NK cells. (C) Summary graph showing the mean±SD of the percentages of IFN-γ positive cells among total CD56^dim and CD56^bright NK cells in PBMC from 5 different donors. ns, not significant; **, p<0.01 using two-tailed Student t test. (D) Overlay histogram showing CD25 and CD69 expression on CD56^dim and CD56^bright NK cells. Filled histogram: NK cells from Control PBS group; Unfilled histogram: NK cells from PBMC treated with PSK (100 μg/ml). Results are representative of 3 independent experiments.