In young but not older subjects CMV infection status was associated with an increase in the level of circulating cytokines indicative of T cell activation (e.g., IFN-γ and IL-13), higher frequencies of CD4+ and CD8+ effector memory T cells, as well as stronger in vitro CD8+ T cell responses to IL-6 activation. The gene discussed is CD8A; the disease is cytomegalovirus infection.