Figure 1.

NK cells' cytotoxic activity is reduced upon MTA co-incubation without affecting NK cell viability. Isolated NK cells were incubated overnight with 100 U/ml IL-2 and pre-incubated for 30′ with various concentrations of MTA at 37°C. NK cells were further incubated for 4 h with the prior MTA concentration in the presence (A) or absence (B) of ⁵¹Cr-labeled K562 cells at a 5:1 ratio. For evaluating NK cells' cytotoxic activity against K562 cells (A; n = 4), the % specific lysis was calculated as followed: [(sample cpm–spontaneous cpm)/(maximal cpm–spontaneous cpm)]^*100. To analyze the effect of MTA on NK cells' viability, they were harvested and stained for Annexin V expression (B; n = 8). Significance was calculated using a one-way ANOVA test (p value: ^* <0.05).