title: [The level of soluble programmed death-1 in peripheral blood of patients with lung cancer and its clinical implications].
abstract: OBJECTIVE
  To analyze the expression of soluble programmed death-1 ligand 1 (sPD-L1) in the serum of patients with lung cancer and to explore its biological and clinical implications.
  
  
  METHODS
  Fifty-five male and twenty-six female lung cancer patients ages 34 to 87 years (mean age 65 ± 6) were selected from the Department of Respiratory Diseases in The Second Affiliated Hospital of Soochow University from June 2009 to March 2011. All lung cancer patients were newly-diagnosed, treatment-free and confirmed by histopathology or cytopathology. Eight-eight healthy volunteers matching in sex and age from the Healthcare Center of the hospital were also enrolled as controls. The sPD-L1 protein expression in serum was determined by Western blot and self-developed ELISA kit. Fluorescence-labeled monoclonal antibody and cytometry were used to examine changes in lymphocyte subsets in the peripheral blood of lung cancer patients and healthy controls.
  
  
  RESULTS
  A higher level of sPD-L1 level in the lung cancer patients [1.6 (0.7 - 7.8) µg/L] was found compared to the control group [0.9 (0.4 - 3.7) µg/L] (P < 0.001). High expression of sPD-L1 in the lung cancer patients was closely correlated to lymph node metastasis and the extent of distant metastasis (χ(2) = 5.636, P < 0.05; χ(2) = 4.601, P < 0.05). The sPD-L1 level in lung cancer patients with objective response to treatment (complete response + partial response) was 2.7 (1.6 - 7.0) µg/L and 1.1 (0.8 - 1.7) µg/L before and after treatment, respectively (P < 0.01). The level of sPD-L1 with progression disease was 1.9 (1.3 - 8.5 µg/L) which was significantly increased compared to the baseline level 1.4 (0.8 - 2.2) µg/L (P < 0.01). Additionally, abnormal changes of T and B lymphocytes and their subsets were found, with a significant decrease of CD(8)(+) T lymphocytes (P < 0.05) and a rise in CD(4)/CD(8) ratio (P < 0.05). Further double-labeling study showed increased percentages of CD(4)(+)PD-1(+) T lymphocytes and CD(8)(+)PD-1(+) T lymphocytes (P < 0.05).
  
  
  CONCLUSIONS
  The elevated expression of sPD-L1 in lung cancer patients was closely related to lung cancer staging, metastasis and clinical response. sPD-L1 may become a predictive marker and an important anti-tumor target in individualized treatment of lung cancer.
authors.affiliation: Department of Respiratory Diseases, the Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Yu-fei
authors.initials: YF
authors.lastname: Xing
authors.forename: Zeng-li
authors.initials: ZL
authors.lastname: Zhang
authors.forename: Min-hua
authors.initials: MH
authors.lastname: Shi
authors.forename: Yu
authors.initials: Y
authors.lastname: Ma
authors.forename: Yong-jing
authors.initials: YJ
authors.lastname: Chen
mesh_terms: D000230:Adenocarcinoma / Q000097:blood* / Q000473:pathology; D000077192:Adenocarcinoma of Lung; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D060890:B7-H1 Antigen / Q000097:blood*; D016516:CD4-CD8 Ratio; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000097:blood* / Q000473:pathology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging
chemical_list: D060890:B7-H1 Antigen