人CD4^+ T细胞在肠道细菌抗原刺激前后CD25与FOXP3的表达

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

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%,CD25hiFOXP3+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+CD25hiFOXP3+T细胞占CD4+CD25hiT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CD25hi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.

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 lymphecytes and monocytes were isolated from 15 people. Some lymphecytes were co-cultured for 14 d with monecytes which were previously challenged by bacterial antigens from autologous intestine. The CD4, CD25 and FOXP3 were measured hy 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^＋ , CD25^hi, FOXP3^＋ , CD25^＋ FOXP3^＋ , and CD25^hi FOXP3^＋ 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 lymphecytes 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 CD^＋ CD25 ^＋ FOXP3^＋ T/CD4^＋ CD25^＋ T or CD4^＋ CD25^hi FOXP3^＋ T/CD4^＋ CD25^＋ 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 CD25^＋ 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.