It can be induced by stress, such as heat shock [14], oxidative stress [15], viral and bacterial infections [16], DNA damage [17], and tumorigenesis [17], acting as danger signals to alert NK cells and the subsets of NKT, CD8+ αβ, and γδ T cells through engagement of the NKG2D activating receptor [7]. The gene discussed is CD8A; the disease is bacterial infectious disease.