Various effector molecules, such as IFN-γ, TNF-α, perforin, FasL, and TRAIL, are utilized by memory CD8 T cells in protection against different infections (Raeder et al., 2000; Trapani and Smyth, 2002; Shrestha et al., 2006, 2008; Ishikawa et al., 2009). The gene discussed is CD8A; the disease is infection.