BCG and protection against Mycobacterium tuberculosis infection

Abstract

I agree with Ahmet Soysal and colleagues that an interferon gamma response to antigens restricted to pathogenic strains of the Mycobacterium tuberculosis complex and not found in bacille Calmette-Guerin (BCG) vaccine may well indicate infection with tubercle bacilli but the absence of such a response does not indicate the absence of infection. Failure to mount an effective interferon gamma response has been associated with susceptibility to mycobacterial disease. In human alveolar macrophages the interferon gamma response to M tuberculosis can be blocked by interleukin 10 which can then promote a Th2 type of immune response. Thus the early interferon gamma response to more specific antigens of M tuberculosis in Soysal and colleagues study might have identified those with a protective immune response to infection rather than those who might later develop tuberculosis. (excerpt)