Expression Of The Costimulatory Molecule PD-L1 In Non-Small Cell Lung Cancer And Tumor Infiltrating Dendritic Cells And Their Significance

Objective:To investigate the expression of the costimulatory molecule PD-L1 in tissues of non-small cell lung cancer and tumor infiltrating dendritic cells, analyze the relationship between PD-L1 expression and clinicopathological parameters and prognosis.Methods:The expression of PD-L1 in 109 NSCLC tissues and para-tumor tissues was evaluated by immunohistochemistry, and the correlation was analysed among the expression of PD-L1, histological types, degree of differentiation, lymphonodes metastasis and survival time after operation. Meanwhile, immunohistochemistry and immunofluorescence double labelling technique were performed to detect the expressions of PD-L1, CD1αand CD83 in 20 DCs, the expression of PD-L1 in CD1α+DCs, CD83+DCs and their significance were explored.Results:(1)Positive expression of PD-L1 was detected in NSCLC tissues and the expression rate was 53.2%. The expression of PD-L1 was associated with histological types and survival time after operation(P<0.05). There was no correlation to be found between PD-L1 expression rate and degree of differentiation, metastasis to lymphonodes and clinical stage. Those patients either with adenocarcinoma or survival time after surgery less than 3 years showed higher expression rate of PD-L1(P<0.05). Furthermore, multivariate analysis indicated that PD-L1 can be regarded as a factor of poor prognosis(P<0.05)(.2)PD-L1+CD1α+DCs were also detected in cancer tissues, most of them were clustering around the tumor cells whereas few were found within tumor interstitial areas and around T lymphocytes. (3)Immunofluorescence double labelling displayed that both CD1α+DCs and CD83+DCs expressed PD-L1. The mean percentage of DCs expressing PD-L1 was (65.68±12.50)% in CD1α+DCs and(37.16±9.52)% in CD83+DCs. Conclusions:(1)PD-L1 could expresse in NSCLC tissues, associated with tumor histological types and prognosis, suggesting that detecting PD-L1 molecule on NSCLC patients would help to estimate the prognosis of patients(.2)PD-L1 was mainly detected in immature CD1α+DCs in NSCLC, showing that tumor micro-environment might upregulate the expression of PD-L1 kept DCs in immature stage and which led to tumor immune escape and disease progression.