Making memories that last a lifetime: heritable functions of self-renewing memory CD8 T cells.

Clonal expansion of virus-specific naive T cells during an acute viral infection results in the formation of memory CD8 T cells that provide the host with long-term protective immunity against the pathogen. Memory CD8 T cells display enhanced effector functions compared with their naive precursors, allowing them to respond more rapidly and effectively to antigen re-encounter. The enhanced functions of memory CD8 T cells are mediated by heritable changes in gene regulation. Expression of select transcription factors along with locus-specific epigenetic modifications are coupled to and are essential in the formation of memory-specific gene expression patterns. Here, we will review the changes in gene expression that accompany development of memory CD8 T cells and discuss chromatin modifications as a potential means for heritable propagation of these changes during homeostatic cell division of self-renewing memory CD8 T cells. Also, we will discuss therapies that manipulate heritable gene regulation as a potential mechanism to restore function to non-functional memory CD8 T cells to combat chronic viral infection.