Polymicrobial sepsis also affects infection and/or vaccine-induced memory CD8 T cell responses by inducing apoptosis of pre-formed memory CD8 T cells and impairing the Ag-dependent and—independent memory CD8 T cell functions (e.g., functional avidity and IFN-γ production upon heterologous infection, respectively) [10,12,13]. This evidence concerns the gene IFNG and infection.