哮喘患儿CD4＋T细胞增殖及活化诱导凋亡机制研究

Proliferation and activation induced cell death of CD4 ＋ T cells in childhood asthma

目的通过体外细胞增殖及活化诱导细胞凋亡试验探讨小儿哮喘免疫炎症及Th细胞过度活化的相关机制。方法哮喘组患儿21例，年龄（9．6±2．3）岁；正常对照组20例，年龄（9．7±1．9）岁。流式液相多重蛋白定量技术检测Th1／Th2／Th17细胞因子；磁珠分离CD4＋T细胞，PHA结合anti—CD3体外刺激后分析其增殖能力及活化后凋亡情况；最后以相对定量PCR测定凋亡及增殖相关蛋白Fas、FasL、Bcl-2的mRNA表达情况。结果哮喘组患儿血清细胞因子水平较正常对照组显著增高[IL-4：（2451±1．052）ng／Lvs（1．796±0．615）ng／L，P=0．018；IL-10：（1．920±0.813）ng／Lvs（1．390±0．162）ng／L，P=0．1306；TNF：（5．112±5．842）ng／Lvs（1．506±0．551）ng／L，P=0．009]；哮喘组CD4＋T细胞增殖能力显著强于正常对照组[OD450：（0．498±0．052）vs（0．274±0．032），P〈0．001]，而活化诱导后细胞凋亡率则显著低于正常对照组[（35．62±0．05）％vs（65．28±3．85）％，P〈0．001]；哮喘组患儿CD4＋T细胞FasmRNA表达较正常对照组显著降低，而Bcl-2表达则显著高于正常对照组，差异均具有统计学意义（P〈0．001），FasL表达差异无统计学意义（P〉0．05）。结论哮喘患儿CD4＋T细胞Fas表达降低及Bcl-2表达升高在一定程度上抑制了Th细胞活化后凋亡并且促进其增殖，而凋亡抑制及细胞增殖可能导致了哮喘患儿Th细胞过度活化和炎性浸润加剧。

Objective To investigate the correlation between immune inflammation and overactivity of T helper cells in childhood asthma by cell proliferation assay and activation induced cell death in vitro. Methods Thl/Th2/Th17 cytokines were determined by cytometric bead array. Cell proliferation and activation induced cell death were detected when CD4 ＋ T cells were purified by magnetic beads and stimulated by PHA and antiCD3. At last, mRNA of Fas, FasL and Bcl-2 were mesured by real-time PCR. Results Cytokines of IL-4 （2. 451 2 1. 052ng/L vs 1. 796 20. 615 ng/L,P = 0. 018）, IL-10（ 1. 920 ± 0. 813ng/L vs 1. 390 2 0. 162ng/L, P = 0. 006） and TNF（5. 112 25. 842 ng/L vs 1. 506 20. 551 ng/L,P =0. 009） in sera of asthma group were higher than those in control group. Compared to control group, proliferation ability of CD4 ＋ T cells in asthma group was greater （ OD450：0. 498 ± 0. 052 vs 0. 274± 0. 032, P 〈 0. 001 ） and apoptosis rate was lower（35.62 ± 0. 05 % vs 65.28 2 3.85 %, P 〈 0. 001 ）. mRNA expression of Fas in asthma group was lower but Bcl-2 was higher than those in control group. Conclusion It is implicated that defective expression of Fas and over expression of Bcl-2 in CD4 ＋ T cells may contribute to apoptosis inhibition and cell proliferation, which could explain overeactivity of CD4 ＋ T cells and lymphocyte infiltration in childhood asthma.