Memory T cell responses have been demonstrated in COVID-19 convalescents, but ex vivo phenotypes of SARS-CoV-2-specific T cells have been unclear. We detected SARS-CoV-2-specific CD8⁺ T cells by MHC class I multimer staining and examined their phenotypes and functions in acute and convalescent COVID-19. Multimer⁺ cells exhibited early differentiated effector-memory phenotypes in the early convalescent phase. The frequency of stem-like memory cells was increased among multimer⁺ cells in the late convalescent phase. Cytokine secretion assays combined with MHC class I multimer staining revealed that the proportion of interferon-γ (IFN-γ)-producing cells was significantly lower among SARS-CoV-2-specific CD8⁺ T cells than those specific to influenza A virus. Importantly, the proportion of IFN-γ-producing cells was higher in PD-1⁺ cells than PD-1⁻ cells among multimer⁺ cells, indicating that PD-1-expressing, SARS-CoV-2-specific CD8⁺ T cells are not exhausted, but functional. Our current findings provide information for understanding of SARS-CoV-2-specific CD8⁺ T cells elicited by infection or vaccination.

已在COVID-19恢复期中证明了记忆T细胞反应，但SARS-CoV-2特异性T细胞的离体表型尚不清楚。我们通过MHC I类多聚体染色检测到SARS-CoV-2特异性CD8 ⁺ T细胞，并检查了它们在急性和恢复期COVID-19中的表型和功能。在恢复期早期，多聚体⁺细胞表现出早期分化的效应记忆表型。在恢复期后期，多聚体⁺细胞中干细胞样记忆细胞的频率增加。细胞因子分泌测定结合MHC I类多聚体染色显示，在SARS-CoV-2特异性CD8 ^+中，产生干扰素-γ（IFN-γ）的细胞比例明显降低T细胞比那些甲型流感病毒特异的。重要的是，IFN-γ产生细胞的比例是在PD-1更高⁺细胞中比PD-1 ^-细胞多聚体间⁺细胞，这表明PD-1表达，SARS-CoV的-2特异性CD8 ⁺ T细胞是不是精疲力尽，而是功能正常。我们当前的发现为理解感染或接种疫苗引起的SARS-CoV-2特异性CD8 ⁺ T细胞提供了信息。