CD8A and viral infectious disease: This not only elicits signals in favor of Th1 immune response but also promotes upregulation of high-affinity IL-12 receptors (IL-12b1/b2), which leads the Th1 cells to be more responsive to IL-12 actions, as well as be useful to amplify the CD8 T lymphocyte resistance to viral infections (74, 76, 77).