Fig. 3: The relationship of local SAA, nuclear p-STAT3, and PD-L1⁺ neutrophils.

a FACS analysis shows the PD-L1 expression on neutrophils exposed to different concentrations of SAA (0, 250, 500, and 1000 ng/mL) for 24 h. Statistical analysis of PD-L1 expression on neutrophils indicates that SAA induced PD-L1 expression on neutrophils in a concentration-dependent manner. n = 4 biologically independent samples. b Flow cytometry images show that PD-L1 is rapidly upregulated after neutrophils are exposed to SAA (1000 ng/mL) for 6 h. n = 5 biologically independent samples. c Western blots show the protein expression of PD-L1, STAT3, and p-STAT3 in neutrophils after being exposed to different concentrations of SAA (0, 0.5, 1, 2.5, 5, and 10 μg/mL) for 24 h. n = 3 independent samples. d Western blots show that the protein expression of STAT3, p-STAT3, PD-L1, and GAPDH in neutrophils is upregulated at different time points (0.5, 6, and 12 h) after SAA exposure (1 μg/mL). n = 3 independent samples. e The six-plex mIHC assay shows the co-expression of SAA (red), p-STAT3 (orange), and PD-L1 (green) in CD15⁺ (yellow) neutrophils from HCC peritumoral specimens. n = 18 patients. f In neutrophils exposed to SAA (1 μg/mL) for 24 h, napabucasin/BBI608, a small molecular STAT3 inhibitor, can significantly reduce the PD-L1⁺ neutrophils via a dose-dependent manner (0.01, 0.1, and 1 μmol/L). n = 6 biologically independent samples. Statistical data presented in this figure show mean ± SEM. ns indicates P > 0.05, *P < 0.05, **P < 0.01 and ****P < 0.0001, by one-way ANOVA (a, b, f), or two-sided Student’s t test (e). Source data and exact P values are provided as a Source Data file.