CD4 and cytomegalovirus infection: Since we have recently shown that CD57 is also a marker of polyfunctional CD4+ T-cells in CMV-seropositive young donors [30] and that the expression of CD300a on CD4+ T-cells is higher in CMV-seropositive aged donors [32], these results support the relevance of CMV infection on the expansion of effector memory and effector polyfunctional CD4+ T-cells that coexpress T-bet and Eomes.