CD8A and influenza: Recent evidence has further shown that the selective loss of primary, influenza-specific CD8+ T cell responsiveness in older mice is characterized by a narrowing in the spectrum of TCR usage that is seen predominantly for low frequency populations, with this effect being best characterized for the prominent DbNP366+ CD8+ T cell set (Yager et al., 2008; Toapanta and Ross, 2009; Valkenburg et al., 2012).