CD8A and neoplasm: In recent years, it has been suggested that effector T cells (CD4+ and CD8+), which infiltrate tumors tend to exhibit impaired functional and proliferating capacity, characterized by progressive loss of their ability to produce their characteristic effector cytokines (i.e., TNF-α, IFN-γ, IL-2) and lyse tumor cells, a state described as lymphocyte exhaustion (45, 151, 207, 266–269).