Steps have been implemented at the various levels of government in the United States, and most institutions where people gather have procedures in place to cope with a pandemic (see Table 1 ). Infl uenza pandemics will not be prevented, but with lessons learned from previous pandemics, the effect of infl uenza pandemics can be reduced. Governments and health professionals must continue to maintain surveillance against all diseases, share information and work together in developing vaccines. As learned in 1918-1919, infl uenza respects no politics, nor borders. Differential Effects of IL-12 on Tregs and Non-Treg T Cells: Roles of IFN-γ, IL-2 and IL-2R Complex interactions between effector T cells and Foxp3(+) regulatory T cells (Treg) contribute to clinical outcomes in cancer, and autoimmune and infectious diseases. Previous work showed that IL-12 reversed Treg-mediated suppression of CD4(+)Foxp3(−) T cell (Tconv) proliferation. We and others have also shown that Tregs express T-bet and IFN-γ at sites of Th1 inflammation and that IL-12 induces IFN-γ production by Tregs in vitro. To investigate whether loss of immunosuppression occurs when IFN-γ is expressed by Tregs we treated mouse lymphocyte cultures with IL-12. IFN-γ expression did not decrease the ability of Tregs to suppress Tconv proliferation. Rather, IL-12 treatment decreased Treg frequency and Foxp3 levels in Tregs. We further showed that IL-12 increased IL-2R expression on Tconv and CD8 T cells, diminished its expression on Tregs and decreased IL-2 production by Tconv and CD8 T cells. Together, these IL-12 mediated changes favored the outgrowth of non-Tregs. Additionally, we showed that treatment with a second cytokine, IL-27, decreased IL-2 expression without augmenting Tconv and CD8 T cell proliferation. Notably, IL-27 only slightly modified levels of IL-2R on non-Treg T cells. Together, these results show that IL-12 has multiple effects that modify the balance between Tregs and non-Tregs and support an important role for relative levels of IL-2R but not for IFN-γ expression in IL-12-mediated reversal of Treg immunosuppression. Natural regulatory T cells (Tregs), identified by the expression of Foxp3, play an important role in down-regulating immune responses and an imbalance between numbers of Tregs and conventional CD4 (Tconv) and CD8 T cells contributes to outcomes in cancer and autoimmune and infectious diseases [1] [2] [3] [4] . Interactions between Tregs and non-Tregs result in modifications of the function of both cell types, with the goal of minimizing detrimental side effects of pro-inflammatory immune responses while maximizing the efficacy of processes such as pathogen clearance. Further, the function of both cell types and the balance between the pro-and anti-inflammatory immune responses may be affected by cytokines and other molecules produced by cells such as dendritic cells, in the inflammatory milieu.