Pieri C, Recchioni R, Moroni F, Marcheselli F, Damjanovich S
Department of Gerontological Research, Italian National Research Centers on Aging I.N.R.C.A., Ancona.
Ann N Y Acad Sci. 1992 Dec 26;673:110-9. doi: 10.1111/j.1749-6632.1992.tb27442.x.
Several parameters generally believed to be necessary for the activation and progression of proliferation of human lymphocytes have been investigated and compared with special reference to aging. The responding capacity of plasma membrane potential to depolarizing and also repolarizing conditions induced by exposure to mitogens like PHA was lower in lymphocytes from old donors as compared to those of young ones. This indicates a significant age-dependent difference in the readiness to respond to channel-activating perturbations. As an early signal of activation, after one hour PHA stimulation the merocyanine 540 uptake by the lipid regions was chosen, based on the property of this fluorescent probe to bind to loosely packed lipids of the plasma membrane. The proteins encoded by the c-myc and c-myb genes were chosen as markers of the G0/G1 and G1/S phased transition, respectively. The mean number of cells that increased the uptake of MC 540 following mitogenic stimulation did not differ in young vs. old individuals. However, 4 samples out of 10 from the old population showed lower MC 540 fluorescence than the lowest signal from the young population. The number of responding cells was decreased during aging when the presence of the c-myc protein was taken as its measure; and this decrease was further accentuated, determining the expression of the c-myb protein. This frequently encountered age-dependent pattern, however, was not followed by the lymphocytes of all old donors. One example is reported in which the MC 540 uptake, the c-myc and c-myb expression in the cells from one old subject fell in the range of the young subjects. However, even in this case, the response of the lymphocytes as measured by 3H-thymidine incorporation was only 64% of that of young subjects. For this sample, we found an impairment of the response at the mitochondrial level. In addition to these parameters, the amount of 3H-thymidine incorporated by the cells expressing the c-myb protein was calculated. The values in old individuals were lower than those in the young, suggesting that not all the cells expressing the c-myb protein were able to synthesize DNA in lymphocyte populations from the elderly. Our data support the view that the age-dependent decline of lymphocyte responsiveness to mitogens can be accounted for by impairments at different levels.(ABSTRACT TRUNCATED AT 400 WORDS)
人们对一般认为人类淋巴细胞增殖激活和进展所必需的几个参数进行了研究，并特别参照衰老情况进行了比较。与年轻供体的淋巴细胞相比，老年供体淋巴细胞的质膜电位对诸如PHA等促有丝分裂原诱导的去极化和复极化条件的反应能力较低。这表明在对通道激活扰动的反应准备方面存在显著的年龄依赖性差异。作为激活的早期信号，基于这种荧光探针与质膜疏松堆积脂质结合的特性，在PHA刺激1小时后选择了部花青540对脂质区域的摄取情况进行研究。分别选择由c-myc和c-myb基因编码的蛋白质作为G0/G1期和G1/S期转变的标志物。有丝分裂原刺激后增加部花青540摄取的细胞平均数量在年轻人和老年人中没有差异。然而，老年人群体的10个样本中有4个显示出比年轻人群体的最低信号更低的部花青540荧光。以c-myc蛋白的存在作为衡量标准时，应答细胞数量在衰老过程中减少；并且这种减少进一步加剧，决定了c-myb蛋白的表达。然而，并非所有老年供体的淋巴细胞都遵循这种常见的年龄依赖性模式。报道了一个例子，其中一位老年受试者细胞中的部花青540摄取、c-myc和c-myb表达都落在年轻受试者的范围内。然而，即使在这种情况下，通过3H-胸苷掺入测量的淋巴细胞反应也仅为年轻受试者的64%。对于这个样本，我们发现在线粒体水平上反应存在缺陷。除了这些参数外，还计算了表达c-myb蛋白的细胞掺入的3H-胸苷量。老年人的值低于年轻人，这表明在老年淋巴细胞群体中，并非所有表达c-myb蛋白的细胞都能够合成DNA。我们的数据支持这样一种观点，即淋巴细胞对促有丝分裂原反应的年龄依赖性下降可以由不同水平的损伤来解释。（摘要截选至400字）
