Gutowski J K, Innes J B, Weksler M E, Cohen S
J Clin Invest. 1986 Jul;78(1):40-3. doi: 10.1172/JCI112570.
Lymphocytes from many elderly individuals exhibit depressed proliferative responses to the plant phytohemagglutinin (PHA). We have previously reported that this proliferative defect is not due to a failure to generate a cytoplasmic activator of DNA replication (ADR). In the present study, we tested the DNA synthetic response of nuclei derived from aged cells to an exogenous source of ADR. We found that nuclei from aged lymphocytes exhibiting low PHA responses were impaired in their ability to synthesize DNA in responses to ADR, compared with nuclei from younger adult donors. In contrast, those aged cells maintaining intact PHA responses provided nuclei that were also unimpaired in their response to ADR. The relationship between PHA responsiveness of the intact cells and ADR responsiveness of nuclei derived from these was a linear one. These results suggest that the depressed cellular reactivity of aged lymphocytes to PHA (when seen) may be due to a failure of these nuclei to respond to cytoplasmic stimulatory signals induced by the mitogen.
许多老年人的淋巴细胞对植物血凝素（PHA）的增殖反应表现出降低。我们之前报道过，这种增殖缺陷并非由于无法产生DNA复制的细胞质激活剂（ADR）。在本研究中，我们测试了来自衰老细胞的细胞核对外源性ADR的DNA合成反应。我们发现，与年轻成年供体的细胞核相比，表现出低PHA反应的衰老淋巴细胞的细胞核在对ADR反应时合成DNA的能力受损。相反，那些保持完整PHA反应的衰老细胞所提供的细胞核对ADR的反应也未受损。完整细胞的PHA反应性与源自这些细胞的细胞核的ADR反应性之间呈线性关系。这些结果表明，衰老淋巴细胞对PHA的细胞反应性降低（如果出现这种情况）可能是由于这些细胞核无法响应有丝分裂原诱导的细胞质刺激信号。
