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.
BACKGROUND: Many types of humantumors 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 cancerpatients. 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.