Reciprocal responsiveness to interleukin-12 and interferon-α specifies human CD8+effector versus central memory T-cell fates

Multiple innate signals regulate the genesis of effector and memory CD8+T cells. In this study, we demonstrate that the innate cytokines interleukin (IL)–12 and interferon (IFN)–α/β regulate distinct aspects of effector and memory human CD8+T-cell differentiation. IL-12 exclusively promoted the development of IFN-γ– and tumor necrosis factor (TNF)–α–secreting T effector memory (TEM) cells, whereas IFN-α drove the development of T central memory (TCM) cells. The development of TEMand TCMwas linked to cell division. In rapidly dividing cells, IL-12 programmed TEMthrough induction of the IL-12 receptor β2. In contrast, IFN-α regulated TCMdevelopment by slowing the progression of cell division in a subpopulation of cells that selectively expressed elevated IFN-α/β receptor-2. The strength of signal delivered through T-cell receptor (TCR) engagement regulated the responsiveness of cells to IL-12 and IFN-α. In the presence of both IL-12 and IFN-α, these cytokine signals were amplified as the strength of the TCR signal was increased, promoting the simultaneous development of both TCMand TEM. Together, our results support a novel model in which IL-12 and IFN-α act in a nonredundant manner to regulate the colinear generation of both effector and memory cells.