Fig. 2

T cells of severe influenza patients highly express PD-1 but not CD38 and HLA-DR, and its expression was associated with that of Ki67. A, B Surface HLA-DR and CD38 expression among gated CD8⁺ and CD4⁺ T cells from healthy donors, moderate and severe influenza patients. C, D Surface PD-1 expression among gated CD8⁺ and CD4⁺ T cells from healthy donors and influenza patients. For each phenotype, the representative FACS plots (in top) and observed expression levels (in bottom) are shown separately. E, F Relationship between the percentage of Ki67⁺ T cells and CD38⁺HLA-DR⁺ T cells for all CD8⁺ or CD4⁺ T cells in moderate and severe influenza patients. G, H Relationship between the percentage of Ki67⁺ T cells and PD-1⁺ T cells for all CD8⁺ or CD4⁺ T cells in influenza patients. Data are displayed as mean ± SEM. Statistical significance is determined by unpaired t test. *P < 0.05, **P < 0.01, ***P < 0.001