From the thymus to longevity in the periphery

Abstract

An important attribute of the adaptive immune system is the ability to remember a prior encounter with a pathogen; an ability termed immunological memory. Bigger, better, and stronger responses are mounted upon a secondary encounter with the pathogen potentially resulting in clearance of the infection before the development of disease. We will review recent advances in the field of memory CD8(+) T cell differentiation focusing on both intrinsic and extrinsic factors that govern the development of T cell memory.

Figure 1. The changing faces of a T cell as it progresses through various life stages

Naïve (N) T cells upon interaction with an antigen bearing DCs undergo activation and clonal expansion, forming a large effector (E) T cell pool. The vast majority of effector cells (senescent effector) undergo apoptosis during the contraction phase. Memory (M) T cells are antigen experienced cells that survive the contraction phase and are classically divided into effector (Tem) or central (Tcm) memory. Cell transitions that are still contentious are depicted with a dotted line.