CD8A and cytomegalovirus infection: Building upon prior hypotheses regarding the expression of GZB in CD8+ T-cells from older adults and the impact of CMV infection thereon (McElhaney et al., 2012), we found that the frequency of cells expressing GZB and its overall level of expression was significantly higher with age in NK-cells, CD8+ and Vδ1+ T-cells, while GZK was higher only in CD8+ T-cells.