Expressions of CD25 and FOXP3 on human CD4+T cells before and after challenged by enteric bacterial antigens

    LIU Xiang1, LIU Fan2, HU Gangª²Zheng1, ZHENG Changª²Qing1

    1Department of Gastroenterology, Shengjing Hospital, China Medical University , Shenyang 110004, China, 2Department of Gastroenterology, Fengtian Hospital, Shenyang Medical College, Shenyang 110024, China

    ¡¾Abstract¡¿ AIM: To investigate expressions of CD25 and FOXP3 on human peripheral blood CD4+ T cells before and after activated by autologous enteric bacterial antigens. METHODS: Human peripheral blood lymphocytes and monocytes were isolated from 15 people. Some lymphocytes were coª²cultured for 14 d with monocytes which were previously challenged by bacterial antigens from autologous intestine. The CD4, CD25 and FOXP3 were measured by flow cytometry on the freshly isolated and the coª²cultured lymphocytes. RESULTS: Of the freshly isolated lymphocytes, about 43.4% expressed CD4. In the CD4+T cells, the percentages of CD25+, CD25hi, FOXP3+, CD25+FOXP3+, and CD25hiFOXP3+T cells were 5.8%, 1.9%, 5.2%, 3.3% and 1.6%, respectively. After in vitro challenged by autologous bacterial antigens, the total number of lymphocytes slightly increased (by 21.0%, P<0.001 vs unchallenged cells). The percentage of CD4+T cells elevated significantly (67.1% vs 43.4%, P<0.001), while the percentages of CD25+, FOXP3+ and CD25+FOXP3+ T cells did not change significantly. The CD4+CD25+FOXP3+T/CD4+CD25+T or CD4+CD25hiFOXP3+ T/CD4+CD25hi T cell ratio decreased (the former from 59.8% to 52.0%; the latter from 86.3% to 77.9%, both P<0.05). CONCLUSION: Both CD25 and CD25hi are not the reliable markers of human regulatory T cells, especially when activated in vitro by bacterial antigens. The activation/proliferation of CD4+CD25+FOXP3- T reactive cells predominates that of CD4+CD25+FOXP3+T regulatory cells in response to the challenge of autologous bacterial antigens. ......