传统树突状细胞 (conventional dendritic cells, cDCs) 对淋巴器官中外周 T 细胞的稳态发挥重要作用，然而这一需求的分子机制一直未明。我们在此研究中展示，特异性缺乏 CD47 的 T 细胞 (Cd47 ΔT 小鼠) 在外周组织中 T 细胞数量显著减少。CD47 缺乏 T 细胞与 cDCs 的直接相互作用导致后者的激活，进而引发前者的壬胞凋亡。Cd47 ΔT 小鼠的 T 细胞缺失和细胞死亡要求其受体信号调节蛋白α在 cDCs 上的表达。Cd47 ΔT 小鼠的 CD4+ T 辅助细胞依赖性接触性过敏反应和细胞毒性 CD8+ T 细胞对肿瘤生长的抑制均明显受损。因此，T 细胞上的 CD47 很可能通过阻止其受 cDCs 引发的壬胞凋亡，从而促进 T 细胞的存活和功能。

Conventional dendritic cells (cDCs) are required for peripheral T cell homeostasis in lymphoid organs, but the molecular mechanism underlying this requirement has remained unclear. We here show that T cell-specific CD47-deficient (Cd47 ΔT) mice have a markedly reduced number of T cells in peripheral tissues. Direct interaction of CD47-deficient T cells with cDCs resulted in activation of the latter cells, which in turn induced necroptosis of the former cells. The deficiency and cell death of T cells in Cd47  ΔT mice required expression of its receptor signal regulatory protein α on cDCs. The development of CD4+ T helper cell-dependent contact hypersensitivity and inhibition of tumor growth by cytotoxic CD8+ T cells were both markedly impaired in Cd47 ΔT mice. CD47 on T cells thus likely prevents their necroptotic cell death initiated by cDCs and thereby promotes T cell survival and function.