Of note, exhausted CD8+ T cells generated upon chronic lymphocytic choriomeningitis virus infection exhibit higher rate of depolarized mitochondria, larger size, and increased ROS level, whereas tumor-infiltrating lymphocytes (TILs), also characterized by exhausted phenotype, show decreased total mitochondrial mass and increased depolarized mitochondria, with fragmented morphology and low level of ROS (42, 43) (Figure 1). This evidence concerns the gene CD8A and neoplasm.