IFN-γ释放试验在结核分枝杆菌潜伏感染诊断中的临床应用价值

Clinical value of interferon-γrelease assays for the diagnosis of a latent tuberculosis infection

目的探讨IFN-γ释放试验(IGRAs)在诊断结核分枝杆菌潜伏感染(LTBI)中的应用价值。方法采用酶联免疫斑点检测法(ELISPOT)测定36名有结核病密切接触者(潜伏感染组)、52例结核病确诊患者(结核病组)以及45名健康者(健康对照组)外周血单个核细胞(PBMC)经ESAT-6/CFP-10刺激后产生IFN-γ的T细胞数量(SFC),并进行结核菌素试验(TST),计算各组ELISPOT阳性率和TST阳性率,比较各组间相关指标的差异。结果潜伏感染组、结核病组、健康对照组的SFC(M)分别为50.5、182.5和8.0,ELISPOT阳性率分别为27.8%、84.6%和0.0%。潜伏感染组SFC数量和ELISPOT阳性率均显著高于健康对照组(P<0.05),但低于结核病组(P<0.05)。潜伏感染组、结核病组、健康对照组的TST试验皮肤硬结平均直径分别为(10.9±5.1)mm、(13.4±3.7)mm和(8.2±5.2)mm,TST阳性率分别为83.3%、94.2%和46.7%。潜伏感染组皮肤硬结平均直径显著大于健康对照组(P<0.05),但小于结核病组(P<0.05)。潜伏感染组TST阳性率显著高于健康对照组(P<0.05),但与结核病组比较差异无统计学意义(P>0.05)。TST阳性率与BGG接种显著相关(P<0.05),而ELISPOT与BGG接种无明显相关P>0.05)。结论IGRAs在LTBI诊断中的临床应用价值优于TST,可用于结核病的辅助诊断。

Objective To examine the clinical value of interferon-γ release assays （IGRAs） for the diagnosis of a latent tuberculosis infection （LTBI）. Methods Subjects were individuals with a history of exposure to tuberculosis （latent tuberculosis （TB） infection group）, patients with confirmed TB （the TB group）, and healthy individuals （control group）. Spot-forming cells （SFC） produced by peripheral blood mononuclear cells （PBMCs） stimulated with ESAT-6/CFP-10 were detected with an enzyme-linked immunospot assay （ELISPOT） in all 3 groups. The tuberculin skin test （TST） was also performed for all subjects. The rate of a positive ELISPOT response and the rate of a positive TST response were calculated and differences in the relevant indicators were compared. Results The number of SFCs （M） was 50.5 in the TB group, 182.5 in the LTBI group, and 8.0 in the control group. The rate of a positive ELISPOT response was 27.8% in the TB group, 84.6% in the LTBI group, and 0.0% in the control group. The number of SFCs and the rate of a positive ELISPOT response were both significantly higher in the LBTI group than in the control group but lower ＂than those in the TB group （P〈0.05）. The average diameter of induration was 10.9±5.1 mm in the TB group, 13.4±3.7 mm in the LTBI group, and 8.2±5.2 mm in the control group. The rate of a positive TST response was 83.3% in the TB group, 94.2% in the LTBI group, and 46.7% in the control group. The average diameter of induration was significantly larger in the LBTI group than that in the control group but smaller than that in the TB group （P〈0.05）. The rate of a positive TST response was significantly higher in the LBTI group than that in the control group （P-0.05） but did not differ sig- nificantly from that in the TB group （P〉0.05）. The rate of a positive TST response was markedly correlated with BGG vaccination but the rate of a positive ELISPOT response was not. Conclusion IGRAs have more clinical value than a TST for the diagnosis of LTBI, and IGRAs should be used widely in the auxiliary diagnosis of TB.