CD8A and neoplasm: The heterogeneous losses of HLA class I either positively or negatively correlate with carcinoma stages or grades in patients [24,27,28], reflecting exactly the situation of carcinoma cells; if carcinoma cancer faces more severe cytotoxicity from NK cells versus CD8+ CTL, certain levels of HLA class I render carcinomas resistance to NK cells; if tumor is under the pressure of CD8+ CTL more than NK cells, then partial loss of HLA class I becomes a key for survival, as indicated by Table 1.