title: Down-regulation of human leukocyte antigens class I on peripheral T lymphocytes and NK cells from subjects in region of high-incidence gastrointestinal tumor.
abstract: BACKGROUND
  Many types of human tumors can suppress the immune system to enhance their survival. Loss or down-regulation of human leukocyte antigens (HLA) class I on tumors is considered to be a major mechanism of tumor immune escape. Our previous studies found that HLA class I on peripheral-blood mononuclear cells was significantly lower in gastric cancer patients. The present study made an analysis of HLA class I expression on peripheral-blood T lymphocytes and NK cells from subjects of Lijiadian village, a village with high-incidence gastrointestinal tumor.
  
  
  METHODS
  A total of 181 villagers from Lijiadian village and 153 normal controls from the Department of Health Examination Center were enrolled in this study. Using a multi-tumor markers detection system, these villagers were divided into two groups: high-risk group (tumor markers positive group) and low-risk group (tumor markers negative group). The percentage of T lymphocytes and NK cells and levels of HLA class I on their surface were determined in these subjects by flow cytometry.
  
  
  RESULTS
  Percentages of T lymphocytes and NK cells in peripheral-blood mononuclear cells did not vary with age. The expression level of HLA class I on peripheral T lymphocytes and NK cells was not affected by age or gender, but was significantly down-regulated in Lijiadian villagers (P < 0.05), especially on the surface of NK cells (P < 0.01). Compared with the low-risk group, there was a significant reduction of HLA class I on peripheral T lymphocytes (P < 0.05) and NK cells (P < 0.05) in the high-risk group.
  
  
  CONCLUSIONS
  HLA class I on peripheral T lymphocytes and NK cells may be involved in tumorigenesis and development of gastrointestinal tumor, and understanding their changes in expression may provide new insights into the mechanism of tumor immunity.
authors: Department of Health Examination Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China. zhangzhimian@126.com
authors: Zhi-Mian
authors: ZM
authors: Zhang
authors: Ying-Jie
authors: YJ
authors: Li
authors: Xiao
authors: X
authors: Guan
authors: Xiao-Yun
authors: XY
authors: Yang
authors: Xi-Mei
authors: XM
authors: Gao
authors: Xiao-Jing
authors: XJ
authors: Yang
authors: Li-Shui
authors: LS
authors: Wang
authors: Xiong
authors: X
authors: Zou
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000032:analysis; D015536:Down-Regulation; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000276:immunology*; D015395:Histocompatibility Antigens Class I / Q000032:analysis*; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D013601:T-Lymphocytes / Q000276:immunology*
chemical_list: D014408:Biomarkers, Tumor; D015395:Histocompatibility Antigens Class I