白细胞介素17对结核病患者中性粒细胞凋亡的影响

目的探讨白细胞介素-17(IL-17)对结核病患者外周血中性粒细胞(PMN)凋亡的影响以及可能涉及的信号通路。方法取结核病患者和健康人外周血PMN培养0~24 h,annexinⅤ染色后流式细胞术检测PMN凋亡率;或加不同浓度IL-17刺激培养24 h再检测PMN凋亡率;或用MAPK特异性抑制剂U0126预处理30 min后,再加IL-17培养24 h后检测PMN的凋亡。结果结核病患者和正常人PMN凋亡率均随培养时间延长而增加(P0.05),结核病患者PMN在0、6、12、24 h时的annexinⅤ+细胞分别为(4.49±1.39)%、(21.89±2.90)%、(39.96±4.15)%、(68.35±7.01)%,均分别高于正常人组的(2.65±0.75)%、(11.00±1.72)%、(25.84±3.90)%,(45.59±4.10)%(P0.05)。而经IL-17刺激后,结核病患者与正常人PMN的凋亡率,在IL-17 0.5μg/L组,分别为(59.81±7.19)%和(34.65±4.79)%;在IL-17 5μg/L组,分别为(51.62±6.91)%和(29.04±3.62)%;均低于未加IL-17对照组(68.35±7.01)%和(45.59±4.10)%(P0.05);而在IL-17 50μg/L组,凋亡率则分别达到(76.04±5.59)%和(53.24±4.62)%,明显高于对照组(P0.05)。预先用U0126处理,可大部分阻断IL-17对结核病患者和正常人PMN凋亡的抑制作用。结论结核病患者和正常人PMN凋亡率均随培养时间延长而增加,且结核病患者PMN凋亡率高于正常人。IL-17较低浓度延迟凋亡,较高浓度促进凋亡。IL-17抑制PMN凋亡的作用和ERK途径有关。     

Th1型和Th2型细胞因子对人中性粒细胞吞噬结核杆菌活性的影响

目的 建立用流式细胞术检测人外周血中性粒细胞(PMNs)吞噬结核分枝杆菌(Mtb)的方法 ,并探讨Th1和Th2型细胞因子对PMNs吞噬Mtb活性的影响.方法 运用抗酸染色、激光共聚焦显微镜观察人PMNs吞噬Mtb,并用流式细胞术检测人PMNs对FTTC标记Mtb的吞噬活性.外周血预先分别与IL-2、IFN-γ、GM-CSF和IL-4等细胞因子孵育,再加FTTC标记Mtb后,用流式细胞术检测PMNs对Mtb吞噬率,并与对照组比较吞噬率的变化.结果 抗酸染色和激光共聚焦显微镜均能观测到人PMNs吞噬Mtb.用流式细胞术检测健康人外周血PMNs对Mtb的吞噬率在5 min时为47%,15～20 min达到平台期,为66%～72%.外周血预先加IL-2或IFN-γ作用后,PMNs对Mtb的吞噬率可分别增加76.7%和75.2%;而预先加IL-4作用后,吞噬率降低31.7%.结论 IL-2和IFN-γ对PMNs吞噬Mtb功能有增强作用,而IL-4有降低作用,表明Th1型和Th2型细胞因子参与调节PMNs抗结核杆菌感染的免疫作用.     

幽门螺杆菌经ROS通路激活NLRP3炎症复合体诱导THP-1细胞分泌IL-1β和IL-18

目的:研究幽门螺杆菌(H.pylori)对NLRP3炎症复合体活化的影响及活性氧(ROS)在其中的作用。方法:将THP-1细胞与H.pylori SS1共孵育,于不同时间点收集细胞及上清,ELISA检测细胞上清中IL-1β和IL-18的含量;流式细胞术(FCM)检测胞内ROS的产生;实时荧光定量PCR(Real-time PCR)检测细胞中NLRP3、caspase-1 mRNA的表达;Western blot检测细胞中caspase-1活性亚单位p10的表达;检测ROS清除剂N-乙酰半胱氨酸(N-acetylcysteine,NAC)及NLRP3特异性小干扰RNA(small interfering RNA,siRNA)预处理细胞后相关信号分子的表达。结果:H.pylori SS1能以时间依赖性和剂量依赖性方式诱导THP-1细胞产生IL-1β、IL-18和胞内ROS;H.pylori SS1刺激能使THP-1细胞NLRP3和caspase-1 mRNA转录水平显著升高;NAC及NLRP3-siRNA预处理THP-1细胞能显著降低H.pylori SS1诱导的NLRP3炎症复合体相关成份的表达及细胞因子的分泌。结论:H.pylori SS1株通过ROS途径激活NLRP3炎症复合体诱导THP-1细胞分泌IL-1β和IL-18,这可能与机体的先天免疫防御及细菌的致病作用相关。     

肺结核患者CD3~+ CD56~+ NKT细胞对IL-2刺激的反应性研究

目的:观察IL-2刺激后肺结核患者CD3+CD56+NKT细胞活化的规律和增殖情况。方法:结核病患者和健康人外周血单个核细胞用IL-2刺激和培养不同时间,采用多色荧光染色和流式细胞术检测NKT细胞的CD69的表达率以及培养前后NKT细胞数量的变化。结果:肺结核患者外周血NKT细胞的比率在刺激培养前与正常人比较无明显差异;经IL-2刺激0、8、16、40和64 h后,患者组和正常组NKT细胞表面CD69的表达量均显著增加,但患者组NKT细胞的CD69表达水平高于正常组(P0.05);培养14 d后,患者组NKT细胞的数量扩增(108.69±59.22)倍,正常组NKT细胞的数量扩增(246.26±134.06)倍,明显高于患者组(P0.05)。结论:肺结核患者外周血NKT细胞在IL-2刺激后表现为高度活化和低增殖的特点。     

布鲁菌S2株诱导小鼠腹腔巨噬细胞凋亡及免疫激活的研究

目的:研究猪布鲁菌S2株诱导巨噬细胞(M(φ))的凋亡、活化及对T淋巴细胞的激活作用.方法:用猪布鲁菌S2株体外感染M(φ),并以大肠埃希菌作为对照,采用瑞氏-姬姆萨染色观察细胞形态学变化;流式细胞仪测定感染后24小时M(φ)的凋亡率;ELISA法检测感染后不同时间点M(φ)培养上清中IL-12和TNF-α及感染后M(φ)与T细胞共培养上清中IFN-γ的含量的变化.结果:瑞氏-姬姆萨染色显示布鲁菌S2株感染M(φ)后1小时体积明显增大,突起增多,胞浆内可见大量布鲁菌;6小时细胞内细菌减少,但胞膜仍完整;至12小时细胞核固缩,胞膜失去完整性.流式细胞仪检测结果显示,感染后24小时M(φ)的凋亡率均明显高于正常对照组及大肠埃希菌感染组(P＜0.05).ELISA结果显示S2株感染M(φ)12、24、48小时的上清中IL-12和TNF-α含量均明显高于正常对照组(P＜0.01),S2株感染后M(φ)与T细胞共培养24、48、72小时产生的IFN-γ量高于正常对照组(P＜0.05),但低于大肠埃希菌感染组(P＜0.01).结论:S2株可以引起M(φ)的凋亡,同时可诱导M(φ)活化,产生IL-12和TNF-α;布鲁菌感染后的M(φ)可诱导T细胞活化,产生IFN-γ免疫应答.     

脱水淫羊藿素对小鼠巨噬细胞免疫功能的影响

目的:研究脱水淫羊藿素(AHI)在体外对脂多糖(LPS)诱导的小鼠巨噬细胞免疫功能的影响。方法:分离制备小鼠骨髓来源巨噬细胞;CCK-8法检测不同终浓度的AHI对巨噬细胞的毒性;采用Griess试剂盒检测AHI对巨噬细胞产生NO的影响;流式细胞术(FCM)检测AHI对巨噬细胞吞噬E.coli颗粒的影响;利用FCM结合双色免疫荧光染色技术检测AHI对巨噬细胞早期活化标志CD69的表达情况;使用流式液相蛋白定量检测技术(CBA)检测AHI对LPS刺激巨噬细胞分泌细胞因子的影响。结果:终浓度为2.5、5、10μmol/L的AHI对活化的小鼠巨噬细胞均具有明显的免疫抑制作用,特别是5μmol/L AHI能明显抑制经LPS刺激的巨噬细胞早期活化,释放NO,吞噬E.coli颗粒,以及分泌IL-6、MCP-1、TNF和IL-12p70四种细胞因子。结论:AHI对LPS诱导的小鼠巨噬细胞的活化具有明显的抑制作用,是一种潜在的免疫抑制剂。     

红景天苷对小鼠腹腔巨噬细胞体外增殖、凋亡、吞噬、ROS和NO产生的影响

目的:研究红景天苷(Sal)对小鼠腹腔巨噬细胞体外增殖、凋亡、吞噬、胞内活性氧簇(ROS)及分泌一氧化氮(NO)的影响,初步探讨其对小鼠腹腔巨噬细胞的免疫调节作用。方法:无菌分离小鼠腹腔巨噬细胞,并制备单细胞悬液,以不同终浓度(80μmol/L、160μmol/L及320μmol/L)的Sal和巨噬细胞共培养4 h,再以脂多糖(LPS)和γ-干扰素(IFN-γ)进行共刺激。利用MTT比色法检测Sal对巨噬细胞体外增殖的影响。用放线菌酮(CHX)诱导巨噬细胞凋亡,用Sytox G reen染色结合荧光酶标仪检测Sal对CHX诱导巨噬细胞凋亡的影响。用流式细胞术(FCM)检测Sal对巨噬细胞吞噬功能的影响。用2-7-二氯氢化荧光素乙二脂(H2DCFDA)染色法结合荧光酶标仪检测Sal对胞内ROS产生的影响;用G riess反应检测Sal对巨噬细胞分泌NO的影响。结果:MTT比色法检测显示,终浓度为80、160、320μmol/L的Sal均可显著促进LPS+IFN-γ刺激巨噬细胞增殖(P<0.05)。荧光酶标仪检测Syto xG reen染色法的结果显示,160μmol/L的Sal可抑制CHX诱导的巨噬细胞凋亡(P<0.01)。FCM结果显示,各浓度的Sal均能促进单纯药物组和实验药物组LPS+IFN-γ刺激巨噬细胞的吞噬功能(P<0.05)。用荧光酶标仪检测DH2DCFDA染色结果表明,各浓度的Sal对LPS+IFN-γ刺激的巨噬细胞胞内ROS的产生均具有显著的抑制作用(P<0.01)。Griess反应检测NO含量的结果显示,各浓度的Sal对LPS+IFN-γ刺激巨噬细胞产生NO均具有促进作用(P<0.05)。结论:Sal对LPS和IFN-γ刺激的巨噬细胞增殖具有显著的促进作用,对CHX诱导的巨噬细胞凋亡具有显著的抑制作用,对静息态和活化态的巨噬细胞的吞噬功能均有增强作用,并能减少LPS和IFN-γ活化的巨噬细胞胞内ROS的产生;但能促进LPS和IFN-γ活化的巨噬细胞NO的分泌。     

连翘提取物对小鼠腹腔巨噬细胞体外吞噬和NO释放的影响

目的:分析连翘(FS)对小鼠腹腔巨噬细胞的体外吞噬和体外NO释放的影响.方法:无菌收集小鼠腹腔巨噬细胞和羧基荧光素乙酰乙酸琥珀酰亚胺酯(CFDA-SE)标记大肠杆菌DH5α,短期培养3 h后流式细胞术(FCM)分析FS对腹腔巨噬细胞体外吞噬的影响.用LPS体外刺激活化腹腔巨噬细胞,Griess Reagent试剂盒检测并分析FS对巨噬细胞体外释放NO的影响.结果:FCM分析显示,终浓度为40、80、160 mg/L的FS对小鼠腹腔巨噬细胞体外吞噬具有明显的促进作用(P<0.05).不同终质量浓度的FS对LPS诱导小鼠腹腔巨噬细胞体外NO的释放均有抑制作用(P<0.05).结论:FS可以促进小鼠腹腔巨噬细胞的体外吞噬和抑制NO体外的释放.     

褐藻多糖硫酸酯体外诱导树突状细胞成熟

目的探讨清道夫受体A(SR-A)非脂蛋白配体,褐藻多糖硫酸酯(Fucoidan),对人体外培养的单核诱导的树突状细胞(monocyte derived DC,MDDC)的影响及其机制。方法采用免疫磁珠法,直接分离外周血单核细胞并通过GM-CSF,IL-4诱导生成MDDC,经Fucoidan或LPS刺激后,用流式细胞技术(FCM)检测树突状细胞表面协同刺激分子表达及细胞吞噬能力的变化;酶联免疫吸附法(ELISA)检测MDDC及Th细胞分泌的细胞因子;CFSE法检测经刺激后MDDC对Th细胞活化、增殖的影响。结果经流式细胞分析术检测,Fucoidan刺激后的MDDC膜表面CD80、CD83及MHC-Ⅱ分子的表达均增强,其中CD83分子表达上调呈剂量依赖性,同时MDDC吞噬能力减弱;IL-10,IL-12p40和TNF-α的分泌增加;并且可以诱导Th细胞的分泌IFN-γ并诱导其增殖。结论 Fucoidan在体外可以诱导MDDC的成熟、活化,刺激其分泌相关细胞因子,发挥其免疫应答中抗原呈递,促进Th活化、增殖分化的作用;通过该作用阐明Fucoidan及SR-A在DC的活化和成熟过程中的作用。     

嗜中性粒细胞抑制LAK及NK细胞的细胞毒作用

用IL-2诱导出LAK,能产生对肿瘤靶细胞的破坏作用。NK细胞是LAK的主要前体细胞,二者细胞毒作用的特点相同。本文检测了外周血多形核中粒细胞(PMN)对LAK、NK 细胞毒作用的影响。体外低浓度IL-2诱导外周血淋巴细胞形成LAK 细胞,对M14瘤株进行释放~(51)Cr的细胞毒试验。在此试验中加入PMN,观察到LAK 的细胞毒作用明显受到抑制,且随     

Rapid diagnosis of Mycobacterium tuberculosis bacteremia by PCR.

A method based on DNA amplification and hybridization has been used for the rapid detection of Mycobacterium tuberculosis in blood samples from 38 hospitalized patients (15 human immunodeficiency virus [HIV] positive and 23 HIV negative) in whom localized or disseminated forms of tuberculosis were suspected. In 32 of these patients, the diagnosis of tuberculosis was eventually confirmed by conventional bacteriological or histological procedures. M. tuberculosis DNA was detected with the PCR technique in the peripheral blood mononuclear cells from 9 of 11 (82%) HIV-infected patients and in 7 of 21 (33%) HIV-negative patients (P < 0.01), while M. tuberculosis blood cultures were positive in 1 of 8 (12.5%) and 1 of 18 (5.5%) patients, respectively. PCR was positive in all cases with disseminated disease in both HIV-negative and HIV-positive patients and also in the HIV-positive patients with extrapulmonary tuberculosis. Seven samples from patients with documented illness other than tuberculosis and 12 specimens from healthy volunteers, including seven volunteers with a recent positive purified protein derivative test, were used as controls and had a negative PCR. These results suggest that detection of M. tuberculosis DNA in peripheral blood mononuclear cells may be a useful tool for rapid diagnosis of disseminated and extrapulmonary forms of tuberculosis, especially in an HIV-positive population.     

M(+) group a streptococci are phagocytized and killed in whole blood by C5a-activated polymorphonuclear leukocytes.

Historically, resistance to phagocytosis has been determined by incubating group A streptococci in human blood and comparing the numbers of CFU before and after incubation. Utilizing a flow cytometry-based technique, we have investigated the phagocytosis of M(+) group A streptococci by polymorphonuclear leukocytes (PMNs) in heparinized human peripheral whole blood. Intracellular labeling of streptococci with a nontoxic fluorescent dye allowed us to quantify the association and phagocytosis of M(+) streptococci by PMNs in whole blood in the presence or absence of C5a, a physiologically important chemotactic activator of PMNs. We found that wild-type strains of group A streptococci that are resistant to phagocytosis (determined by the classical Lancefield method) readily associate with C5a-activated whole-blood PMNs. In the absence of opsonizing M-type-specific antibodies, the M(+) streptococci associated with PMNs are phagocytized and killed. In addition, blockade of the beta(2) integrin, CD11b/CD18, with anti-human CD11b monoclonal antibody inhibited association between M(+) streptococci and C5a-activated PMNs. These findings establish a new relationship between M(+) streptococci and PMNs, in which C5a-activated PMNs have the capacity to kill M(+) streptococci in whole blood through a receptor-mediated phagocytic mechanism.     

Interleukin 17-Producing γδ T Cells Increased in Patients with Active Pulmonary Tuberculosis

Although it has been known that γδ T cells may play an important role in the immune response to infection of Mycobacterium tuberculosis （M. tb）, the mechanisms by which the γδ T cells participate in the innate and/or acquired immunity to tuberculosis （TB） have not been full elucidated. In the present study, 27 patients with active pulmonary TB and 16 healthy donors （HD） were performed. We found that proportion of IL-17-producing cells among lymphocyte was similar between TB patients and HD, whereas the proportions of γδ T cells in IL-17-producing cells （59.2%） and IL-17-producing cells in γδ T cells （19.4%） in peripheral blood were markedly increased in TB patients when compared to those in HD （43.9% and 7.7%, respectively）. In addition, the proportions of IFN-T-producing γδ T cells in TB patients were obviously lower than that in HD. Upon re-stimulated with M. tb heat-treated antigen （M. tb-HAg） in vitro, fewer IL-17-producing γδ T cells were generated from HD and TB patients, whereas IFN-T-producing γδ T cells were increased in TB patients compared to that in HD. Our findings in TB patients and healthy human were consistent with other murine investigation that the IL-17- producing γδ T cells were main source of IL-17 in mouse model of BCG infection, suggesting that γδ T cells might be involved in the formation of tubercular granuloma in pulmonary TB patients, but need further identification.     

结核分枝杆菌多抗原蛋白芯片对儿童结核病的诊断价值

目的探讨结核分枝杆菌（MTB）多抗原蛋白芯片对儿童结核病的诊断价值。方法选取2005年4月至2006年4月在首都医科大学附属北京儿童医院诊断为结核病的住院患儿作为结核病组。选取同期住院，患感染性疾病，同时除外结核病的患儿作为非结核病组；选取体检纯化蛋白衍生物（PPD）试验阳性，既往无结核病史，无明显结核中毒症状，胸部影像学及腹部B超检查未见结核病灶的儿童作为结核感染组；选取同期行健康体检，卡疤试验阳性，无基础疾病，无结核接触史的儿童为健康对照组。各组留取血清标本。计算结核病组PPD试验阳性率及细菌学检查阳性率。应用MTB多抗原蛋白芯片同时检测标本中脂阿拉伯甘露糖（LAM）、相对分子质量16000和38000蛋白IgG抗体，通过蛋白芯片阅读仪判断结果，其中任意1种或1种以上抗体检测阳性，即判为蛋白芯片检测阳性。分别计算各组抗体检测阳性率，并计算该方法检测儿童结核病的灵敏度、特异度、阳性预测值和阴性预测值等指标。应用Logistic回归及，检验分析蛋白芯片检测阳性率与患儿年龄、病程、抗结核治疗时间、激素使用以及结核病类型的关系。结果研究期间共纳入结核病组79例，非结核病组33例，结核感染组15例，健康对照组30例。蛋白芯片检测结核病组的阳性率为34．2％（27／79），低于PPD试验阳性率（84．8％，67／79），高于细菌学检查阳性率（12．7％，10／79）。在非结核病组阳性率为6．1％（2／33），结核感染组和健康对照组阳性率为0。蛋白芯片检测结核病组的灵敏度为34．2％，特异度为97．4％。阳性预测值93．1％，阴性预测值58．5％。Logistic回归发现蛋白芯片检测阳性率仅与病程相关，且随病程延长而阳性率升高。病程〈1个月，蛋白芯片检测阳性率为18．8％（6／32），病程在～3个月，蛋?     

Performance of nucleic acid amplification following extraction of 5 milliliters of whole blood for diagnosis of Mycobacterium tuberculosis bacteremia

To investigate the performance of a nucleic acid amplification test (NAAT) for the diagnosis of Mycobacterium tuberculosis bacteremia, 5-ml aliquots of blood were inoculated into bioMérieux mycobacterial (MB) bottles and incubated, and 5-ml aliquots of blood were extracted and tested by real-time PCR. Of 25 samples from patients with M. tuberculosis bacteremia, 9 (36.0%) were positive and 1 (1.5%) of 66 control samples was positive by NAAT. The NAAT shows promise, but modifications should focus on improving sensitivity.     

T-cell responses to CD1-presented lipid antigens in humans with Mycobacterium tuberculosis infection

CD1-restricted presentation of lipid or glycolipid antigens derived from Mycobacterium tuberculosis has been demonstrated by in vitro experiments using cultured T-cell lines. In the present work, the frequency of T-cell responses to natural mycobacterial lipids was analyzed in ex vivo studies of peripheral blood lymphocytes from human patients with pulmonary tuberculosis, from asymptomatic individuals with known contact with M. tuberculosis documented by conversion of their tuberculin skin tests, and from healthy tuberculin skin test-negative individuals or individuals vaccinated with Mycobacterium bovis BCG. Proliferation and gamma interferon enzyme-linked immunospot assays using peripheral blood lymphocytes and autologous CD1(+) immature dendritic cells revealed that T cells from asymptomatic M. tuberculosis-infected donors responded with significantly greater magnitude and frequency to mycobacterial lipid antigen preparations than lymphocytes from uninfected healthy donors. By use of these methods, lipid-antigen-specific proliferative responses were minimally detectable or absent in blood samples from patients with active tuberculosis prior to chemotherapy but became detectable in blood samples drawn 2 weeks after the start of treatment. Lipid antigen-reactive T cells were detected predominantly in the CD4-enriched T-cell fractions of circulating lymphocytes, and anti-CD1 antibody blocking experiments confirmed the CD1 restriction of these T-cell responses. Our results provide further support for the hypothesis that lipid antigens serve as targets of the recall response to M. tuberculosis, and they indicate that CD1-restricted T cells responding to these antigens comprise a significant portion of the circulating pool of M. tuberculosis-reactive T cells in healthy individuals with previous exposure to M. tuberculosis.     

A rapid evaluation of phagocytosis and killing of Candida albicans by CD13+ leukocytes

Flow cytometry can be adopted for routine monitoring of the immune functions of human polymorphonuclear leukocytes (PMNs) in several disease states. We recently developed a rapid and reproducible assay for the evaluation of the phagocytosis and killing of Candida albicans blastospores by human PMNs. Whole blood leukocytes were incubated with opsonized fluorescein isothiocyanate-labeled (FITC-labeled) blastospores for phagocytosis and killing assays. To discriminate between ingested, membrane-bound and free C. albicans blastospores, ethidium bromide (EtBr) was added to the samples prior to the flow cytometric analysis. EtBr induces a loss of green fluorescence in non-phagocytized C. albicans blastospores. Phagocytosis is determined by gating the phagocytes and calculating the percentage of phagocyte-associated green fluorescent cells. Intracellular killing is determined by first lysing phagocytes by hypotonic shock and then adding propidium iodide (PI) in order to identify red dead blastospores. Killing is measured in terms of the percentage of double-marked blastospore cells. We suggest that this method is a reliable and inexpensive technique to evaluate the immune reactivity of PMNs and peripheral blood monocytes (PBMs) in cases of immunosuppression.     

Expression of toll-like receptor 2 and plasma level of interleukin-10 are associated with outcome in tuberculosis

Toll-like receptor (TLR) 2-mediated innate immunity is an important defense system against Mycobacterium tuberculosis infection. Studies on TLR2 protein expression and downstream cytokines in tuberculosis patients are lacking. TLR2 expression in the peripheral blood monocytes of 87 tuberculosis patients and 94 healthy subjects was evaluated using flow cytometry. TLR2 expression and its downstream cytokines, including interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-alpha, and interferon-gamma, were correlated with the clinical manifestations and outcomes of tuberculosis. The TLR2 expression in peripheral blood monocytes was higher in tuberculosis patients than in healthy subjects. Among the tuberculosis patients, those aged ≥70 years with disseminated tuberculosis or aged <70 years with symptom duration ≥14?days had lower initial TLR2 expression. After two months of treatment, TLR2 expression decreased in most patients, except in those whose sputum samples remained culture-positive for M. tuberculosis. Proportional hazards regression analyses revealed that high initial TLR2 expression and IL-10 plasma level were associated with shorter survival. TLR2 may play an important role in the course of tuberculosis. Its expression on peripheral blood monocytes and the plasma level of the downstream anti-inflammatory cytokine IL-10 may be important outcome predictors and have potential use in the management of tuberculosis patients.     

变性高效液相色谱法检测结核分枝杆菌gyrA基因突变

目的 分析我国结核分枝杆菌氟喹诺酮类耐药基因gyrA突变的特点并探讨变性高效液相色谱法(DHPLC)的应用价值.方法 以结核分枝杆菌临床分离株109株(常规药敏试验显示87株氧氟沙星耐药,22株敏感)为对象,测定氧氟沙星最小抑菌浓度(MIC),同时进行gyrA基因氟喹诺酮类耐药决定区域(QRDR)DNA测序及DHPLC分析.结果 发现我国耐氧氟沙星结核分枝杆菌近来出现两个新的特点:一是gyrA QRDR双位点突变率高(87株耐药株中56.3%携有双位点突变);二是出现了以往认为的仅存在于其他细菌而在结核分枝杆菌中从未报道过的Ala74Ser突变(49株双位点突变耐药株中有20.4%携有该突变).gyrA基因突变类型与MIC之间并无密切关系.DHPLC测定中除常规的M.tb H37Rv以外还引入了M.tb Erdman做为参照菌株,成功地摆脱了95位AGC:ACC自然多态性的影响.与测序法相比较,DHPLC法的敏感度与特异度均达100%.结论 我国结核分枝杆菌氟喹诺酮类耐药已很严重,gyrA基因QRDR双位点突变率高为其特点.本研究建立的结核分枝杆菌gyrA基因突变的DHPLC分析法简便快速,稳定灵敏,在大面积大样本耐药监测以及临床快速药敏检测中有应用价值.