Fig. 3. PD-L1 expression on endothelial cells affects the proliferation and activation of immune cells.

a PBMC was extracted from normal blood and treated with 2.5 µg/ml anti-CD3 antibody and IL-2 (100 U/ml) for 72 h, and co-cultured with tumor-derived endothelial cells (Td-EC) for 48 h. b HUVECs were treated with the supernatant of tumor cells (CM) for 48 h. c PBMC and Td-EC were treated with control, anlotinib (0.1 μm) or anti-PD-L1 antibody (4 μg/ml). d Detection of the CD8⁺ IFN-γ⁺, CD8⁺Ki67⁺, CD8⁺GranzymeB⁺, and FoxP3⁺ T cells by flow cytometry. e Quantification of the above positive cells in the immune cells. f Quantification of cytokine levels in co-culture supernatants (2 days) by liquid microarray. Data are mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, Student’s t test.