人 CD4+T细胞在肠道细菌抗原刺激前后CD25与FOXP3的表达

目的：探讨新鲜分离及自身肠道菌群抗原刺激后的人外周血CD4^＋T细胞CD25和FOXP3表达的相关性及变化规律．方法：分离人的外周血单核细胞和淋巴细胞，单核细胞经自身肠道菌群抗原刺激后与淋巴细胞混合培养，新鲜分离及混合培养14d的淋巴细胞用三色流式细胞术在单细胞水平同时检测CD4，CD25和FOXP3的表达．结果：新鲜分离的淋巴细胞约43．4％表达CD4，在CD4^＋T细胞中，约5．8％表达CD25，而高表达的只有1．9％，约5．2％表达FOXP3，CD25和FOXP3均表达的占3．3％，CD25^hi FOXP3^＋细胞占1．6％，CD4^-细胞几乎不表达FOXP3．经抗原刺激后，淋巴细胞总数均轻度增加（与未刺激组比较，平均增加21．0％，P〈0．001）．CD4^＋细胞的比例均明显上升（67．1％vs43．4％，P〈0．001），CD25^＋，FOXP3^＋及CD25^＋FOXP3^＋细胞的比例变化不大．CD4^＋CD25^＋FOXP3^＋T细胞占CD4^＋CD25^＋T细胞的比例及CD4^＋CD25^hi FOXP3^＋T细胞占CD4^＋CD25^hiT细胞的比例在所有研究对象中均呈下降趋势（前者从59．8％降到52．0％，后者从86．3％降到77．9％，均P〈0．05）．结论：CD25和FOXP3的表达具有一定的相关性，但CD25及CD25^hi均不能很可靠地标记人类的调节性T细胞，尤其是在淋巴细胞受到抗原刺激以后．肠道菌群抗原作为外来抗原刺激自身的淋巴细胞后，活化增殖的细胞中主要是CD4^＋CD25^＋FOXP3^-反应性T细胞，而不是CD4^＋CD25^＋FOXP3^＋调节性T细胞．

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

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 co-cultured 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 co-cultured 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.