Lightstone E B, Wyllie D, Marvel J
ICRF Tumor Immunology Unit, University College London, GB.
Eur J Immunol. 1991 Sep;21(9):2161-5. doi: 10.1002/eji.1830210926.
In vitro studies have suggested that the presence of CD45RA on subsets of CD4 and CD8 cells defines naive T cells and that, in response to antigen, CD45RA+ cells become CD45RA- along a differentiation pathway. To test the hypothesis that CD45RA+ cells are naive cells which have just left the thymus, young mice were thymectomized. This would be predicted to lead to a fall in the size of the peripheral pool of CD45RA+ T cells. However, the changes in the size of this pool would also be dependent on the life-span and self renewal capacity of the CD45RA+ T cells in the periphery. Therefore, to test the contribution of the thymus to the peripheral CD45RA+ pool, the percentage of CD45RA+ cells among spleen lymphocyte subsets was studied from 10 days up to 2 years of age in thymectomized and control mice. We also studied the expression of the memory marker CD44 on the CD45RA subsets of CD4 and CD8 cells, as well as the effect of in vitro activation on expression of CD45RA. Our results show that CD8+ CD45RA+ cells are mainly CD44- and their maintenance is dependent on the presence of the thymus. In contrast, the majority of CD4+ CD45RA+ are CD44+ and are not affected by thymectomy. This indicates that the maturation stage of CD8+ CD45RA+ cells is different from that of CD4+ CD45RA+ cells.
体外研究表明，CD4和CD8细胞亚群上CD45RA的存在定义了初始T细胞，并且在抗原刺激下，CD45RA+细胞会沿着分化途径转变为CD45RA-细胞。为了验证CD45RA+细胞是刚离开胸腺的初始细胞这一假设，对年轻小鼠进行了胸腺切除。预计这将导致外周CD45RA+ T细胞池的大小下降。然而，该细胞池大小的变化也将取决于外周CD45RA+ T细胞的寿命和自我更新能力。因此，为了测试胸腺对外周CD45RA+细胞池的贡献，研究了胸腺切除小鼠和对照小鼠从10天到2岁的脾淋巴细胞亚群中CD45RA+细胞的百分比。我们还研究了CD4和CD8细胞的CD45RA亚群上记忆标志物CD44的表达，以及体外激活对CD45RA表达的影响。我们的结果表明，CD8+ CD45RA+细胞主要为CD44-，其维持依赖于胸腺的存在。相反，大多数CD4+ CD45RA+细胞为CD44+，且不受胸腺切除的影响。这表明CD8+ CD45RA+细胞的成熟阶段与CD4+ CD45RA+细胞不同。
