On Our Way to a Better Understanding of CD8 T Cell Differentiation and Memory T Cell Development.

As certain acute viral or bacterial infections resolve, two types of effector CD8 T cells are formed that differ in their longevity and memory T-cell potential. These cell types can be distinguished from one another by surface markers, namely IL-7R and KLRG1. Memory precursor effector cells are enriched in the IL-7Rhi KLRG1lo cell population, and short-lived effector cells are enriched in the KLRGhi IL-7Rlo population. These two populations become discernible during the peak of clonal expansion. Upon expression of KLRG1, the effector cells are committed to becoming short-lived. Our recent progress toward identifying the signals and genetic pathways that control the formation of these different types of effector T cells will be discussed.