title: Increased PD-1 expression on CD4+ and CD8+ T cells is involved in immune evasion in gastric cancer.
abstract: BACKGROUND
  Co-signaling molecules play an important role in T cells. Programmed death-1 (PD-1) is an immunoinhibitory receptor and its overexpression on T cells appears to be involved in immune evasion in cancer patients. The present study was designed to investigate PD-1 expression on T cells and its relationship with immune evasion in gastric cancer patients.
  
  
  METHODS
  PD-1 expression on CD4+ and CD8+ T cells obtained from peripheral blood mononuclear cells (PBMC), normal gastric mucosa, and gastric cancer tissue was evaluated by multicolor flow cytometry.
  
  
  RESULTS
  PD-1 expression on CD4+ and CD8+ T cells from gastric cancer patients was significantly higher than that from normal controls. PD-1 expression on CD4+ and CD8+ T cells was related to disease progression. Furthermore, PD-1 expression on CD4+ and CD8+ T cells from gastric cancer tissue was significantly higher than that from normal gastric mucosa and PBMC. PD-1 positive CD4+ and CD8+ T cells produced significantly less IFN-gamma than PD-1 negative CD4+ and CD8+ T cells.
  
  
  CONCLUSIONS
  Upregulation of PD-1 on both CD4+ and CD8+ T cells may be, in part, responsible for immune evasion in gastric cancer patients.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Tottori University School of Medicine, Yonago, Japan. sai10@med.tottori-u.ac.jp
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Saito
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Kuroda
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Matsunaga
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Osaki
authors.forename: Masahide
authors.initials: M
authors.lastname: Ikeguchi
mesh_terms: D000368:Aged; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000378:metabolism; D008297:Male; D009000:Monocytes / Q000378:metabolism; D061026:Programmed Cell Death 1 Receptor / Q000378:metabolism*; D013274:Stomach Neoplasms / Q000276:immunology* / Q000473:pathology; D015854:Up-Regulation
chemical_list: D018950:Lipopolysaccharide Receptors; C105992:PDCD1 protein, human; D061026:Programmed Cell Death 1 Receptor; D007371:Interferon-gamma