Flament-Saillour M, Perronne C
Service des Maladies Infectieuses et Tropicales, Hôpital Raymond-Poincaré, Garches.
Rev Mal Respir. 1997 Dec;14 Suppl 5:S27-32.
Though most often asymptomatic, tuberculous infection induces a delayed hypersensitivity reaction in the host by activating cellular immunity thus rendering the host refractory, "a priori", to a new infection; at least provided that the infecting dose is not massive or that the immune system of the host is not compromised. Less that ten per cent of immuno-competent individuals infected by Mycobacterium tuberculosis will develop tuberculous disease during their life. The intradermal reaction (IDR to tuberculin) in revealing delayed hypersensitivity to Mycobacterial antigens is in the absence of obvious signs, the only means of diagnosing a tuberculous infection in an individual. It is performed in France by an intradermal injection of 0.1 mls (10 U) of Merieux tuberculin. The response is read at 72 hours. In those who have not had BCG vaccination, an area of induration with a diameter of greater than or equal to 10 mm gives a positive result and is evidence of a tuberculous infection. The test is negative if the diameter is less than 5 mm and indeterminate between 5 and 9 mm. These indeterminate reactions may be the consequence of previous BCG vaccination or of a contact with atypical Mycobacteria in the environment. An IDR of greater than or equal to 10 mm less than ten years after BCG vaccination would not permit any discrimination between a reaction to the vaccine or an authentic tuberculous infection. On the other hand, an IDR of greater than 10 mm ten years after BCG vaccination is evidence of renewed contact with wild tubercle bacilli in 88 per cent of cases. In individuals whose immune defence is altered in particular in patients infected with HIV the threshold of positivity for IDR is lowered to 5 mm.
虽然结核感染大多无症状，但它通过激活细胞免疫在宿主体内引发迟发型超敏反应，从而使宿主“先天”对新感染具有抵抗力；至少前提是感染剂量不大或宿主免疫系统未受损。免疫功能正常的个体感染结核分枝杆菌后，一生中患结核病的比例不到10%。皮内反应（结核菌素皮内反应）在无明显体征的情况下揭示对分枝杆菌抗原的迟发型超敏反应，是诊断个体结核感染的唯一方法。在法国，通过皮内注射0.1毫升（10单位）的梅里埃结核菌素进行该测试。在72小时读取反应结果。对于未接种卡介苗的人，硬结直径大于或等于10毫米为阳性结果，表明存在结核感染。如果直径小于5毫米，测试为阴性；直径在5至9毫米之间则结果不确定。这些不确定反应可能是先前接种卡介苗或接触环境中非典型分枝杆菌的结果。接种卡介苗后不到十年，皮内反应大于或等于10毫米无法区分是对疫苗的反应还是真正的结核感染。另一方面，接种卡介苗十年后皮内反应大于10毫米，在88%的病例中表明再次接触了野生结核杆菌。对于免疫防御功能改变的个体，特别是感染艾滋病毒的患者，皮内反应阳性阈值降至5毫米。
