Expression of programmed death ligand-1 in human glioma and its influence to intratumor infiltrating T lymphocyte apoptosis / 重庆医学

ABSTRACT

Objective To investigate the expression of programmed death ligand-1(PD-L1) in glioma and its influence to intratumor infiltrating T lymphocyte apoptosis.Methods PD-L1 in 18 cases of normal brain tissues and 80 cases of glioma tissues treated in this hospital during 2007 to 2011 was determined by immunohistochemistry staining,meanwhile the PD-L1 expression in glioma infiltrating T lymphocyte was determined.The correlation analysis was performed.The apoptosis of intratumor infiltrating lymphocytes was examined by TUNEL assay;the peripheral blood activated T lymphocyte apoptosis promoted by PD-L1 was analyzed by flow cytometry.Results No expression of PD-L1 in normal brain tissues was observed,but the positive expression rate in glioma was 42.50 ％ (34/80),which was correlated with pathological grade,necrosis and prognosis(P＜0.05).PD-1 was expressed in part of tumor infiltrating T lymphocytes and glioma tissues,moreover the lymphocyte apoptosis expression in the cases of PD-L1 positive glioma was significantly increased compared with that in the cases of PD-L1 negative glioma.The apoptosis rate of activated T lymphocytes was 42.55 ％ respectively,which was significantly higher than that in the blank group;however,adding anti-PD-1 for blocking the combining of PD-L1 with T lymphocyte,the lymphocytes apoptotic rate in the PD-L1+ anti-PD-1 group was dropped to 26.80％.Conclusion PD-L1has aberrantly high expression in human glioma and is combined with PD-1 to promote the apoptosis of lymphocyte.