Abstract:Objective To investigate the expression of programmed cell death protein 1(PD-1), programmed cell death 1 ligand 1 (PD-L1) and tumor infiltrates lymphocytes (TIL) density in neuroblastoma and the relationship between them and the clinicopathological features of patients. Methods The postoperative tumor tissues of 58 patients with neuroblastoma who underwent surgical resection in Shanxi Children ‘s Hospital from January 2000 to June 2022 were selected, and the expression of PD-1 in tumor lymphocytes and PD-L1 in tumor cells were detected by immunohistochemical method. T lymphocyte density of CD3+, CD4+ and CD8+ was detected. The expression of PD-1 and PD-L1 and the relationship between T lymphocyte density of different subgroups and clinicopathological characteristics were analyzed. Results The positive expression rates of PD-1 and PD-L1 protein were 44.8% and 43.1%, respectively. There were significant differences in the expression of PD-L1 in INSS stage, INRGSS stage, pathological type and differentiation type (P<0.05). PD-1 expression was significantly different in different tumor location, INSS stage and INRGSS stage (P<0.05). PD-1 was correlated with PD-L1 expression (r=0.318, P=0.011). The density of tumor infiltrating T cells was significantly different in different INSS stage and INRGSS stage (P<0.05). The expression of CD3+T cells around the nest, CD3+T cells in the nest and CD8+T cells around the nest were correlated with the expression of PD-1 (r=0.265, 0.287, 0.309, P＜0.05.) Conclusion High expression of PD-L1 in neuroblastoma predicts worse prognosis, and tumor-infiltrating T lymphocytes may be involved in the regulation of PD-1 expression. Immunotherapy targeting PD-1/PD-L1 signaling pathway is expected to be a potential therapeutic target for neuroblastoma.