Future studies to differentiate the mechanisms for different effectors and Treg cell frequency fluctuations may address the possibility that cytokines like IL-2, IL-10 and TGF-β are known to induce Tregs from naive T cells [50,51] and thus, if fluctuating in cancer patients, may promote time-dependently conversion of naive T cells to Tregs rather than effector T cells. Here, IL2 is linked to cancer.