Fig. 1

Peripheral neutrophils exhibit upregulated surface level of PD-L1 during sepsis. A, B Peripheral blood neutrophils were isolated from septic patients and healthy controls. Proportion of PD-L1⁺ neutrophils (A) and MFI of PD-L1 on neutrophils (B) were determined by flow cytometry. C Representative flow cytometry image of PD-L1 levels on neutrophils from septic patients and healthy controls. D, E An in vitro simulation of neutrophils under septic condition was established by LPS (1ug/ml) stimulation of dHL-60 cells for 2 h, 4 h, 6 h and 8 h (n = 4). Proportion of PD-L1⁺ dHL-60s (D) and MFI of PD-L1 on dHL-60s (E) were determined by flow cytometry. F Representative flow cytometry image of PD-L1 levels on dHL-60s subjected to different durations of LPS stimulation. Mann Whitney test and one-way ANOVA were performed. Data are presented as the mean ± SEM. *P < 0.05; **P < 0.01; ****P < 0.0001. NS, not significant