TNF and leukemia: Although NKG2C+ NK cells were more reactive to cytokine stimulation than NKG2C− NK cells in terms of their IFN-γ, TNF-α, and CD107a+GZB+ (p < 0.0001, p = 0.0005, and p = 0.0324, respectively; n = 10) response, we did not observe the same profile differences after incubation with K562 leukemia cells, as only TNF-α production was slightly increased in the latter situation (p = 0.0066, n = 10).