IL2 and neoplasm: The frequencies of CD25+CD127lo Treg cells correlated negatively with total T cell IFN-γ and IL-2, suggesting that these Treg cells may inhibit antitumor effector responses; however, there was no correlation between Treg cells and T cell IL-17 or TNF-α, both of which have been suggested to have pro-tumor activity (30, 31).