Torfadottir H, Freysdottir J, Skaftadottir I, Haraldsson A, Sigfusson G, Ogmundsdottir H M
Faculty of Medicine, University of Iceland, Reykjavik, Iceland.
Clin Exp Immunol. 2006 Sep;145(3):407-12. doi: 10.1111/j.1365-2249.2006.03139.x.
Our previous study showed that children who had been partially or completely thymectomized during heart surgery as infants had lower proportions and numbers of total lymphocytes and reduced proportions of T cells (CD3(+)), helper T cells (CD4(+)) and naive T cells (CD3(+) CD4(+) CD45RA(+)), but normal proportion of cytotoxic T cells (CD8(+)). In this study T lymphocytes from a selected group of eight of these children and age- and gender-matched controls were characterized further using flow cytometry to determine phenotypes of T cells and T cell subsets related to T cell regulation and phenotypes suggestive of extrathymic maturation. Immune function was assessed by measuring autoantibodies and antibodies against vaccines. The study group had significantly lower numbers of all the main subsets of T lymphocytes and the composition was different. Thus, the proportions of lymphocytes with the following phenotypes: CD3(+), CD2(+), CD7(+), CD4(+), CD62L(+), CD4(+) CD62L(+) and CD4(+) CD69(-) were significantly reduced in the study group compared with the control group, but significantly higher proportions were seen of lymphocytes expressing CD8alpha(+) CD8beta(-) and TCRgammadelta(+) CD8alpha(+) CD8beta(-). The absolute number and proportion of CD4(+) CD25(+) cells were reduced but the proportions of the subgroup of naive regulatory T cells (CD4(+) CD25(+) CD62L(+)) and non-activated regulatory T cells (CD4(+) CD25(+) CD69(-)) were not reduced in the thymectomized children. We conclude that the phenotypic characteristics of T lymphocytes of children who have lost their thymus in infancy are indicative of extrathymic maturation. T regulatory cells appear to be less affected than other subsets by the general reduction in T cell numbers.
我们之前的研究表明，婴儿期心脏手术时接受部分或完全胸腺切除术的儿童，其总淋巴细胞比例和数量较低，T细胞（CD3(+)）、辅助性T细胞（CD4(+)）和初始T细胞（CD3(+) CD4(+) CD45RA(+)）比例降低，但细胞毒性T细胞（CD8(+)）比例正常。在本研究中，使用流式细胞术对从这些儿童中挑选出的8名儿童以及年龄和性别匹配的对照组的T淋巴细胞进行了进一步表征，以确定与T细胞调节相关的T细胞和T细胞亚群的表型以及提示胸腺外成熟的表型。通过测量自身抗体和疫苗抗体来评估免疫功能。研究组所有主要T淋巴细胞亚群的数量显著减少，且组成不同。因此，与对照组相比，研究组中具有以下表型的淋巴细胞比例显著降低：CD3(+)、CD2(+)、CD7(+)、CD4(+)、CD62L(+)、CD4(+) CD62L(+)和CD4(+) CD69(-)，但表达CD8alpha(+) CD8beta(-)和TCRgammadelta(+) CD8alpha(+) CD8beta(-)的淋巴细胞比例显著更高。CD4(+) CD25(+)细胞的绝对数量和比例降低，但胸腺切除儿童中初始调节性T细胞亚群（CD4(+) CD25(+) CD62L(+)）和未激活调节性T细胞（CD4(+) CD25(+) CD69(-)）的比例未降低。我们得出结论，婴儿期失去胸腺的儿童T淋巴细胞的表型特征表明胸腺外成熟。T调节细胞似乎比其他亚群受T细胞数量普遍减少的影响更小。
