Expression of the genes encoding human leucocyte antigens-A, -B, -DP, -DQ and -G in gastric cancer patients.

This study compared the expression of the genes encoding human leucocyte antigens (HLA)-A, -B, -DP, -DR and -G in peripheral blood mononuclear cells (PBMCs) in gastric cancer patients and healthy controls. Using reverse transcription-polymerase chain reaction, levels of classical HLA-A, -B, -DP and -DR and non-classical HLA-G mRNA were studied in 43 gastric cancer patients and 22 controls. In addition, the levels of HLA-A,B,C and -G antigens on the surface of PBMCs were measured in 30 gastric cancer patients and 15 controls using flow cytometry. The mean fluorescence intensity of HLA-A,B,C antigen in the gastric cancer group was significantly lower than in controls. The HLA-G antigen was mainly present on CD4 + CD8 - T-lymphocytes. The percentage of CD4 + CD8 - T-lymphocytes positive for HLA-G antigen was significantly lower in the gastric cancer group compared with the healthy controls. Levels of HLA-A, -B and -G mRNA in the gastric cancer group were significantly lower than in controls. The HLA-G mRNA levels were significantly lower in gastric cancer of histological grades III and IV than in grades I and II. These data may provide a novel diagnostic and research tool for gastric cancer.