Patients and samples
PB samples of primary NSCLC patients (Adenocarcinoma, n=27; Squamous cell lung cancer, n=23) and healthy donors (n=50) were obtained from Nanjing Drum Tower Hospital from April 2018 to December 2019. Cancer cases were confirmed by pathological diagnosis. According to the results of surgery, cancer staging was determined according to the 6th edition of the American Joint Cancer Commission’s tumor-node-metastasis (TNM) staging system. All NSCLC patients were diagnosed for the first time and had not received any treatment before. Detailed information of NSCLC patients were listed in Table 1. Collected samples were firstly subjected to centrifuge at 20ºC, 2000 rpm for 5 min to separate the cells from plasma. ACK buffer was used to lyse red blood cells (RBCs), and the remaining cells were used for following experiments. To confirm the potential application of PMN-MDSC frequency in NSCLC diagnosis, we also collected paired PB samples from NSCLC patients at 3 months after surgical resection. Meanwhile, PB samples of NSCLC patients with or without recurrence after surgery were collected to identify the association of PMN-MDSC proportion with NSCLC recurrence (n=50). All samples were obtained in accordance with the approval of the Ethics Committee of Nanjing Drum Tower Hospital. All experiments were undertaken with the understanding and written consent of each subject.