Treatment of MP2 with fixed NK cells treated with IL-2 + anti-CD16mAb + sAJ2 + anti-TNF-α had slight enhancing effect on tumor growth, whereas fixed NK cells obtained from anti-IFN-γ in combination with IL-2 + anti-CD16mAb + sAJ2-treated NK cells enhanced tumor cell growth substantially. This evidence concerns the gene IL2 and neoplasm.