Weindruch R, Devens B H, Raff H V, Walford R L
J Immunol. 1983 Feb;130(2):993-6.
Natural killer cells (NK) are believed to defend against tumor growth. Because rodents subjected to dietary restriction without malnutrition live longer and develop spontaneous tumors less often or later in life than unrestricted controls, we measured NK activity in restricted and in unrestricted mice. An age-related decline in NK responses to YAC-1 tumor target cells was detected in both groups. NK responses for control mice were highest in 2- to 3-mo-old mice, sharply reduced in middle-age mice (14 to 15 mo), and slightly reduced further in old mice (30 to 33 mo). At all ages the response of restricted mice was less than that of controls. However, after injection with Poly I:C (which increases NK activity), old restricted mice showed NK cytolysis not different from young mice on either diet, and substantially higher responses than old unrestricted mice. In addition, restricted mice showed increased in vitro generation of cytotoxic T lymphocytes (CTL) to YAC-1 and P815 compared with age-matched controls. Restricted mice may better resist cancer via an NK system very responsive to induction signals coupled with a CTL system more effective than that of unrestricted controls.
自然杀伤细胞（NK）被认为可以抵御肿瘤生长。由于未出现营养不良的饮食限制啮齿动物比未受限制的对照动物寿命更长，且在生命后期发生自发性肿瘤的频率更低或更晚，我们测量了受限制和未受限制小鼠的NK活性。在两组中均检测到NK对YAC-1肿瘤靶细胞反应的年龄相关性下降。对照小鼠的NK反应在2至3月龄小鼠中最高，在中年小鼠（14至15月龄）中急剧降低，而在老年小鼠（30至33月龄）中进一步略有降低。在所有年龄段，受限制小鼠的反应均低于对照小鼠。然而，注射聚肌胞苷酸（可增加NK活性）后，老年受限制小鼠的NK细胞溶解作用与任何一种饮食条件下的年轻小鼠均无差异，且反应显著高于老年未受限制小鼠。此外，与年龄匹配的对照相比，受限制小鼠对YAC-1和P815的细胞毒性T淋巴细胞（CTL）体外生成增加。受限制小鼠可能通过对诱导信号反应灵敏的NK系统以及比未受限制对照更有效的CTL系统更好地抵抗癌症。
