Figure 2

PD-1 and PD-L1 were upregulated on T cells and monocytes in septic shock patients. Blood samples were obtained from 19 septic shock patients and 22 healthy controls and were stained for programmed death-1 (PD-1) and programmed death ligand-1 (PD-L1) gated on CD4⁺ T cells, CD8⁺ T cells, and CD14⁺ monocytes. (a) to (c) Percentage of PD-1 expression on (a) CD4⁺ T cells and (b) CD8⁺ T cells, and (c) percentage of PD-L1 expression on CD14⁺ monocytes. Each dot represents one individual. Data are mean ± standard error of the mean (SEM) of three independent experiments. **P < 0.01 compared with healthy controls. (d) to (f) Mean fluorescence intensity (relative fluorescence units) of PD-1 expression on (d) CD4⁺ T cells, (e) PD-1 expression on CD8⁺ T cells, and (f) PD-L1 expression on CD14⁺ monocytes Each dot represents one individual. Data are mean ± SEM of three independent experiments. *P < 0.05 compared with healthy controls. (g) Representative PD-1 expression levels on CD4⁺ T cells and CD8⁺ T cells, and PD-L1 expression on CD14⁺ monocytes. Values in the upper-right quadrant indicate the percentage of cells that express PD-1 or PD-L1.