Memory T-cell homeostasis and senescence during aging

Abstract

Evidence is accumulating that old individuals are more susceptible to infection with organisms to which they were previously immune, indicating that there might be a limit to the persistence of immune memory. The prevailing concept is that defects in memory T-cell populations result from inexorable end-stage differentiation as a result of repeated lifelong antigenic challenge. We discuss here mechanisms that might constrain the persistence of memory T cells and consider whether humans will suffer from memory T-cell exhaustion as life expectancy increases.