These cells have the capacity to kill autologous malignant T cells ex vivo and high numbers of lesional CD8 T cells are associated with a favorable prognosis, indicating that the cellular immune reaction in early disease represents an anti-tumor response that keeps the malignant population in check (Hoppe et al., 1995; Berger et al., 1996; Bagot et al., 1998; Vermeer et al., 2001; Abeni et al., 2005). The gene discussed is CD8A; the disease is neoplasm.