Abstract: Objective To investigate the effect of small interfering RNA (siRNA)-mediated silencing of programmed cell deathligand 1 (PD-L1) in human glioma cells on the cytotoxicity of human CD8+T lymphocytes against the modified tumor cells. Methods A siRNA sequence targeting PD-L1 gene was designed and transfected into human glioma U87 MG cells via lipofectamine 2000, and the gene silencing effect was validated using RT-qPCR, Western blotting, and flow cytometry. The transfected cells were co-cultured with human CD8+T lymphocytes, and the apoptosis of the tumor cells was analyzed with flow cytometry. Results The siRNA sequence showed strong PD-L1 gene-silencing effect at both mRNA and protein levels in U87 MG cells. Compared with the control cells, the transfected U87 MG cells showed significantly increased vulnerability to the cytotoxicity of human CD8+T cells and an obvious reduction of proliferative activity in the co-culture (P<0.05). Conclusion Transfection of human glioma U87 MG cells with the specific siRNA targeting PD-L1 obviously enhances the toxicity of human T lymphocytes in the co-culture.