Li Y M, Brunke D L, Dantzer R, Kelley K W
Department of Animal Sciences, University of Illinois, Urbana 61801.
Endocrinology. 1992 May;130(5):2703-9. doi: 10.1210/endo.130.5.1572290.
Although implantation of GH3 pituitary epithelial cells has been shown to reverse thymic aging in rats, the differentiation pattern of T-lymphocytes within the reconstituted thymus glands has not been investigated. Syngeneic GH3 cells were implanted into 22-month-old female (old) Wistar-Furth rats. Eight weeks later, thymus glands and thymocyte subpopulations were compared to those in aged (24-month-old) and young (3-month-old) female Wistar Furth rats. We confirmed that implantation of GH3 cells increased (P less than 0.05) not only thymus size but also the number of thymocytes isolated from aged rats. Flow cytometric analysis using dual color direct immunofluorescence with fluorescein isothiocyanate-labeled anti-CD4 (W3/25) and phycoerythrin-labeled anti-CD8 (OX 8) monoclonal antibodies revealed that thymus glands from young rats had approximately 20% CD4-CD8- and 30% CD4+CD8+ cells. Thymus glands from old rats contained greater than 50% more CD4-CD8- cells and a reduced percentage of CD4+CD8+ lymphocytes compared to those of young rats (P less than 0.05). Moreover, both of these age-associated changes were reversed (P less than 0.05) by implanting GH3 cells. GH3-treated aged rats also had a significantly (P less than 0.05) greater proportion of CD4+CD8- thymocytes compared to aged control rats. There were no differences among the three groups of rats in the percentage of CD4-CD8+ thymocytes or in the percentage or intensity of cells expressing the T-cell markers CD3, T-cell receptor, or OX19. These results show that in aged rats, intrathymic maturation is inhibited at the key transitional stage where double negative cells differentiate into double positive cells, which may limit the diversity of the T-cell repertoire. The data also extend earlier results by demonstrating that GH3 epithelial cells promote not only growth, but also the differentiation of T-lymphocytes in the aging rat thymus.
虽然已证明植入GH3垂体上皮细胞可逆转大鼠胸腺衰老，但重组胸腺内T淋巴细胞的分化模式尚未得到研究。将同基因的GH3细胞植入22月龄雌性（老年）Wistar-Furth大鼠体内。8周后，将胸腺和胸腺细胞亚群与老年（24月龄）和年轻（3月龄）雌性Wistar-Furth大鼠的进行比较。我们证实，植入GH3细胞不仅增加了（P<0.05）老年大鼠的胸腺大小，还增加了从老年大鼠分离出的胸腺细胞数量。使用异硫氰酸荧光素标记的抗CD4（W3/25）和藻红蛋白标记的抗CD8（OX 8）单克隆抗体进行双色直接免疫荧光的流式细胞术分析显示，年轻大鼠的胸腺中约有20%的CD4-CD8-细胞和30%的CD4+CD8+细胞。与年轻大鼠相比，老年大鼠的胸腺中CD4-CD8-细胞多50%以上，CD4+CD8+淋巴细胞的百分比降低（P<0.05）。此外，通过植入GH3细胞，这两个与年龄相关的变化均得到逆转（P<0.05）。与老年对照大鼠相比，经GH3处理的老年大鼠CD4+CD8-胸腺细胞的比例也显著更高（P<0.05）。三组大鼠在CD4-CD8+胸腺细胞百分比、表达T细胞标志物CD3、T细胞受体或OX19的细胞百分比或强度方面没有差异。这些结果表明，在老年大鼠中，胸腺内成熟在双阴性细胞分化为双阳性细胞的关键过渡阶段受到抑制，这可能会限制T细胞库的多样性。数据还扩展了早期结果，证明GH3上皮细胞不仅促进衰老大鼠胸腺的生长，还促进T淋巴细胞的分化。
