Sester Urban, Junker Heike, Hodapp Tobias, Schütz Alexandra, Thiele Bernhard, Meyerhans Andreas, Köhler Hans, Sester Martina
Department of Internal Medicine IV, Nephrology, University of the Saarland, D-66421 Homburg, Germany.
Nephrol Dial Transplant. 2006 Nov;21(11):3258-68. doi: 10.1093/ndt/gfl416. Epub 2006 Aug 25.
Reactivation of a latent Mycobacterium tuberculosis infection in immunocompromised individuals is associated with significant morbidity and mortality. The limited sensitivity of the established tuberculin skin-test in identifying latently infected patients on immunosuppressive drug therapy represents a major obstacle to better tuberculosis control after transplantation.
In this study, a quantitative flow-cytometric whole-blood assay and the skin-test were comparatively evaluated towards both diagnostic power and practicability in 117 long-term renal transplant recipients (age 53.1+/-14.8 years; 7.0+/-5.0 years after transplantation) in a low-prevalence region.
Among the aforementioned renal transplant recipients, a high proportion (52.14%) had purified protein-derivative (PPD)-specific T-cell-immunity in vitro. Despite immunosuppression, prevalence as well as median frequencies of PPD-specific T-cells (0.22%; >0.05-4.71%) were as high as previously reported for immunocompetent individuals and haemodialysis patients. In contrast to in vitro testing, skin testing was less practicable in an ambulatory setting. Moreover, skin-test reactivity was significantly reduced as only 50.0% of patients with PPD-reactivity in vitro were skin-test positive. T-cell reactivity towards early secretory antigenic target-6 (ESAT-6), a protein specific for M. tuberculosis but absent from the bacillus Calmette-Guerin BCG-vaccine strain, was found in 52.9% of all individuals with PPD-reactivity in vitro.
In conclusion, the whole-blood assay reveals a high prevalence of latent tuberculosis infection in renal transplant recipients. It may represent a valuable alternative to skin testing as the test result is not adversely affected by immunosuppression. Moreover, reactivity towards ESAT-6 allows the distinction of a latent infection from BCG-induced reactivity. The assay is well-suited for use in screening programmes and may facilitate the management of tuberculosis infection in immunocompromised individuals.
免疫功能低下个体中潜伏性结核分枝杆菌感染的重新激活与显著的发病率和死亡率相关。已有的结核菌素皮肤试验在识别接受免疫抑制药物治疗的潜伏感染患者方面敏感性有限，这是移植后更好地控制结核病的一个主要障碍。
在本研究中，对117名长期肾移植受者（年龄53.1±14.8岁；移植后7.0±5.0年）在一个低流行地区进行了定量流式细胞术全血检测和皮肤试验，比较了两者的诊断能力和实用性。
在上述肾移植受者中，很大一部分（52.14%）在体外具有纯化蛋白衍生物（PPD）特异性T细胞免疫。尽管存在免疫抑制，但PPD特异性T细胞的患病率和中位频率（0.22%；>0.05 - 4.71%）与之前报道的免疫功能正常个体和血液透析患者一样高。与体外检测相比，皮肤试验在门诊环境中不太实用。此外，皮肤试验反应性显著降低，因为体外PPD反应性患者中只有50.0%的皮肤试验呈阳性。在所有体外具有PPD反应性个体中，52.9%的个体发现了对早期分泌性抗原靶标6（ESAT - 6）的T细胞反应性，ESAT - 6是结核分枝杆菌特有的一种蛋白，但卡介苗（BCG）疫苗株中不存在。
总之，全血检测显示肾移植受者中潜伏性结核感染的患病率很高。它可能是皮肤试验的一种有价值的替代方法，因为检测结果不受免疫抑制的不利影响。此外，对ESAT - 6的反应性可以区分潜伏感染和卡介苗诱导的反应性。该检测非常适合用于筛查项目，并可能有助于免疫功能低下个体的结核病感染管理。
