Study on the Expression Levels and Clinical Significance of PD-1 and PD-L1 in Plasma of NSCLC Patients

As new members of the CD28/B7 costimulatory superfamily, PD-1 (programmed cell death 1) and its ligand PD-L1 (programmed cell death ligand 1) mediate a negative costimulatory signal, which inhibits functioning and proliferation of T and B cells, and reduce interleukin-2, interleukin-10, and interferon-gamma secretion. This inhibitory pathway plays an important role in immune escape and the microenvironment of the tumor, and closely related to tumor progression. sPD-1 and sPD-L1 are the soluble form of PD-1 and PD-L1 in peripheral blood, which had not been well investigated. In this study, sPD-1 and sPD-L1 level in peripheral blood of non-small cell lung cancer (NSCLC) patients were determined, and their correlation to clinicopathologic features and long-term survival of these patients were analyzed, so as to provide references for further investigations. Plasma sPD-1 and sPD-L1 levels in 88 NSCLC patients and 40 healthy controls were determined by enzyme-linked immunosorbent assay, and their correlation to clinicopathologic features and long-term survival of these patients were analyzed. Our study showed that the plasma sPD-1 and sPD-L1 were higher in NSCLC patients than in healthy controls, and plasma sPD-L1 and sPD-L1/sPD-1 ratio independently and positively correlated with overall survival of NSCLC patients. This study provides a reference for the assessment of prognosis and risk stratification for NSCLC patients, as well as for immune treatment of cancer.