Potential effector cells responsible for tumor killing include MHC-restricted cytotoxic T cells (CD8+ CTL) and CD4+ T cells [4, 5], MHC-nonrestricted cells such as natural killer (NK) cells [6–8], lymphokine-activated killer (LAK) cells [8, 9] and BCG-activated killer (BAK) cells [10–12], CD1-restricted CD8+ T cells [13], γδ T cells [14–16], natural killer T (NKT) cells [15–17], neutrophils [18, 19], and macrophages [20–22]. Here, CD8A is linked to neoplasm.