CD4~+Foxp3~+T细胞亚群在系统性红斑狼疮中的免疫抑制功能研究

采用五色流式细胞术检测系统性红斑狼疮(systemic lupus erythematosus,SLE)患者和健康对照组的CD4+Foxp3+T细胞及其细胞亚群;以CFSE染色法分析SLE患者和健康对照组CD4+Foxp3+T细胞各亚群的免疫抑制功能。结果发现SLE组CD4+Foxp3+T细胞(占CD4+T细胞的比例)显著高于对照组(12.03%±1.523%vs 6.410%±0.4353%,t=3.790,P<0.01),但其CD4+T细胞的增殖却比对照组活跃(PI:4.052%±0.4004%vs 2.528%±0.2322%,t=3.293,P<0.05)。根据Foxp3和CD45RA表达强度的差异,可将CD4+Foxp3+T细胞清晰地分成3个亚群:CD45RA+Foxp3low(Ⅰ区)细胞、CD45RA-Foxp3high(Ⅱ区)细胞和CD45RA-Foxp3low(Ⅲ区)细胞,SLE组的Ⅰ区和Ⅲ区细胞数量显著增加(分别为t=2.123,P<0.05;t=3.462,P<0.01),而Ⅱ区细胞与对照组之间差异无统计学意义(0.6056%±0.1879%vs0.6571%±0.1764%,t=0.1999,P>0.05)。SLE患者和健康对照者的Ⅰ区和Ⅱ区细胞在体外均具有免疫抑制功能,而Ⅲ区细胞不具有该功能。SLE患者Ⅰ区细胞的免疫抑制能力弱于对照组(t=2.994,P<0.05),而Ⅱ区细胞和Ⅲ区细胞与对照组之间差异均无统计学意义。提示,SLE患者CD4+Foxp3+T细胞比例升高而免疫抑制功能下降,可能是两大原因造成了这种数量和功能的不一致性:①SLE患者CD4+Foxp3+T细胞数量增加主要由于Ⅲ区细胞增多所致,而这区细胞不具有免疫抑制功能;②在SLE患者,具有免疫抑制功能的Ⅰ区细胞的抑制能力明显减弱。

Study on the distribution,subsets and suppressive function of CD4~+ Foxp3~+ T cells in systemic lupus erythematosus

Five-color flow cytometry was applied to determine CD4+Foxp3+ T cells and their subsets in patients with systemic lupus erythematosus(SLE);Carboxyfluorescein succinimidyl ester(CFSE) labelling method was used to analyze immunosuppressive function of the total CD4+Foxp3+ T cells and its subsets in patients with SLE.Compared with the healthy donors,the proportion of CD4+Foxp3+ T cell among CD4+ T cells was increased(12.03%±1.523 % vs 6.410%±0.4353%,t=3.790,P<0.01),and the proliferation of CD4+ T cell was more active(PI: 4.052%±0.4004% vs 2.528%±0.2322%,t=3.293,P<0.05) in patients with SLE.By the combination of Foxp3 and CD45RA staining,human CD4+Foxp3+ T cells could be distinctly separated into three subpopulations: CD45RA+Foxp3low cells(Fr.Ⅰ),CD45RA-Foxp3high cells(Fr.Ⅱ) and CD45RA-Foxp3 low cells(Fr.Ⅲ).The proportion of Fr.Ⅰ and Fr.Ⅲ among CD4+ T cells were increased significantly in patients with SLE(t=2.123,P<0.05;t=3.462,P<0.01),while no significant increase was found in Fr.Ⅱ.In vitro experiments showed that either in patients with SLE or in healthy donors,Fr.I and Fr.Ⅱ were suppressive,whereas Fr.Ⅲ was no suppressive.Compared with healthy donors,the suppressive potency of Fr.Ⅰ was weaker in SLE(t= 2.994,P<0.05).In patients with SLE,two main reasons may account for the discrepancy between the increased cell number and the dropped suppressive function of CD4+Foxp3+ T cells in SLE patients: 1) The increase in number of CD4+Foxp3+ T cells is contributed mainly by the nonsuppressive Fr.Ⅲ.2) While the suppressive function of FI CD4+Foxp3+ T cells was significantly weakened.