Naive CD4 T Cells from Aged Mice Show Enhanced Death Upon Primary Activation

Poor T cell immunity is one of the many defects seen in elderly humans and aged (Ad) mice. We report that naive CD4 T cells from aged mice (ANCD4 cells) showed greater apoptosis upon primary activation than those from young (Yg) mice, with loss of mitochondrial membrane potential, poor activation of Rel family transcription factors and increased DNA damage. Their ability to enhance glycolysis, produce lactate and induce autophagy following activation was also compromised. ANCD4 cells remained susceptible to death beyond first cell division. Activated ANCD4 cells also showed poor transition to a 'central memory' (CM) CD44(high), CD62L(high) phenotype in vitro. This correlated with low proportions of CM cells in Ad mice in vivo. Functionally, too, IFN-gamma responses recalled from T cells of immunized Ad mice, poor to begin with, worsened with time as compared with Yg mice. Thus, ANCD4 cells handle activation-associated stress very poorly due to multiple defects, possibly contributing to poor formation of long-lasting memory.