Apoptosis in myelogenous leukemia K562 cells treated with NK-92 cells either cultured alone or with SW1990 cells in the absence or presence of MMP-9 and/or IDO blockers. (A) Flow cytometric analysis of apoptosis in K562 cells treated with NK-92 cells with 1-MT and/or TIMP-1, at an effector-to-target (E/T) ratio 9:1. (B) The percentages of apoptotic K562 cells treated with NK-92 cells at different E/T ratios (1:1, 3:1 and 9:1), show that the addition of 1-MT and/or TIMP-1 blockers upregulates apoptosis in K562 cells. (C,
E) Comparisons between the concentrations of GM-CSF, TNF-α and IFN-γ in the supernatants from the different NK cell-pancreatic cell culture groups. All experiments were repeated three times. All data were expressed as mean ± SD. Independent t-tests were used for statistical analysis through SPSS 19.0 software. *represents P <0.05, **represents P <0.01, and ***represents P <0.001.