Multiple Choices

The generation of memory T cells in immune responses has been extensively studied over recent years, yet the requirements for production and persistence of a functional memory pool are still unclear. For example, while there is compelling evidence that survival of memory cells does not require TCR–MHC engagements (1, 2), recent evidence indicates that such interactions may be needed to maintain functional activity of these cells (3, 4). Furthermore, there is growing evidence that cytokines play a major role in deciding the fate of CD8 memory cells, although the precise mechanisms by which these effects are mediated remain unknown.