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HLA class I down-regulate on peripheral T lymphocytes and NK cells of gastrointestinal tumor

Human leukocyte antigens (HLA) class I are cell surface glycoproteins which play important roles in the regulation of immune responses. It is known that total or partial loss of HLA class I on tumor cells is one of the main mechanisms of tumor escape. T lymphocytes and NK cells, as the two critical effector cells of immune defense, also express plentiful HLA class I.

The percentage of T lymphocytes and NK cells and  levels of HLA class I on their surface can be determined by flow cytometry. The result showed that percentages of T lymphocytes and NK cells in peripheral-blood mononuclear cells did not vary with age. Meanwhile, the expression level of HLA class I on peripheral T lymphocytes and NK cells was not affected by age or gender, either. But compared with the low-risk group, there was a significant reduction of HLA class I on peripheral T lymphocytes and NK cells in the high-risk group.

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.

Figure 1 The gates of peripheral-blood T lymphocytes, NK cells and HLA class I expression. A: Total lymphocytes were separated from peripheral-blood (Gate 1).  B: T lymphocytes (Gate 2) and NK cells (Gate  3) were separated from total lymphocytes.  C: Mean fluorescence intensity of HLA class I on T lymphocytes. D: Mean fluorescence intensity of HLA class I on NK cells.

Reference: Zhang ZM, Li YJ, Guan X, Yang XY, Gao XM, Yang XJ, Wang LS, Zou X. Down-regulation of human leukocyte antigens class I on peripheral T lymphocytes and NK cells from subjects in region of high-incidence gastrointestinal tumor. Chin Med J (Engl) 2011, 124(12):1813-7.