Programmed death-1 receptor (PD-1) and PD-ligand-1 (PD-L1) expression in non-small cell lung cancer and the immune-suppressive effect of anaerobic glycolysis

The microenvironment of a tumor may regulate the anti-tumor immune response. Intratumoral acidosis and hypoxia may suppress lymphocyte proliferation and migration, and this may have important implications in modern immunotherapy. The expression of PD-L1 by cancer cells and of PD-1 by tumor infiltrating lymphocytes (TILs) was assessed in tissue specimens from 98 operable NSCLC patients. Their prognostic role and their association with makers of glycolysis and anaerobic metabolism were assessed. Strong cytoplasmic/membrane PD-L1 expression was noted in 45/98 cases. Intense presence of TILs was noted in 42/98 cases (high TIL-score), and intense presence of PD-1 expressing TILs (high PIL-score) in 17/98 cases. PD-L1 expression was directly correlated with high PIL-score ( p = 0.005). A significant inverse relationship was found between lactate dehydrogenase LDH5 expression and PIL-score ( p = 0.008). Similarly, low PIL-score was significantly linked with high-hexokinase HXKII and monocarboxylate transporter MCT2 expression ( p