Eren R, Globerson A, Abel L, Zharhary D
Department of Cell Biology, Weizmann Institute of Science, Rehovot, Israel.
Cell Immunol. 1990 May;127(2):238-46. doi: 10.1016/0008-8749(90)90129-f.
Our studies on the capacity of bone marrow (BM) to generate T lymphocytes in aging have revealed that under the competitive conditions of thymic reconstitution, cells of aged mice are significantly inferior to those of the young. The present study was designed to further investigate the basis of this age-related change. Two mechanisms were considered: (a) The potential of BM-derived T cell precursors from aged mice to proliferate and differentiate in the thymic microenvironment is impaired. (b) The frequency of T cell precursors is reduced in BM of aged mice, thus affecting their ability to compete efficiently in reconstituting the thymus. These possibilities were studied in vitro by colonizing thymocyte-depleted fetal thymic lobes with BM cells from aged (24-month) and young (3-month) C57BL/6 mice. By determining the cell cycle duration of BM-derived cells which have seeded the thymic lobes, we found that cells originating from aged mice proliferate in the thymus at the same rate as those from young mice. Reconstitution with limiting numbers of BM cells indicated that the frequency of thymic progenitors in the BM is significantly reduced in aged as compared to young mice. We thus conclude that aging is associated with a quantitative reduction in the frequency of thymic progenitors in the BM.
我们关于衰老过程中骨髓（BM）产生T淋巴细胞能力的研究表明，在胸腺重建的竞争条件下，老年小鼠的细胞明显不如年轻小鼠的细胞。本研究旨在进一步探究这种与年龄相关变化的基础。我们考虑了两种机制：（a）老年小鼠骨髓来源的T细胞前体在胸腺微环境中增殖和分化的潜力受损。（b）老年小鼠骨髓中T细胞前体的频率降低，从而影响它们在重建胸腺中有效竞争的能力。通过用来自老年（24个月）和年轻（3个月）C57BL/6小鼠的骨髓细胞接种胸腺细胞耗竭的胎儿胸腺叶，在体外研究了这些可能性。通过确定接种到胸腺叶中的骨髓来源细胞的细胞周期持续时间，我们发现来自老年小鼠的细胞在胸腺中的增殖速度与来自年轻小鼠的细胞相同。用有限数量的骨髓细胞进行重建表明，与年轻小鼠相比，老年小鼠骨髓中胸腺祖细胞的频率显著降低。因此，我们得出结论，衰老与骨髓中胸腺祖细胞频率的定量减少有关。
