Management of tuberculosis in HIV infection: where T-cells matter

Abstract

Even 127 years after Robert Koch's identification of Mycobacterium tuberculosis as the causative agent of tuberculosis (TB), the diagnosis of active disease still depends in many parts of the world on the same tools that Koch has used: specifically staining of the bacilli and visual observation by microscopy 1. Thirty years later, von Pirquet developed the tuberculin skin-test (TST), which, instead of observing the pathogenic microbe itself, measures the immunological response to it 2. We now know that the specific induration in the skin-test is mediated by specifically activated T-lymphocytes that elicit a delayed-type hypersensitivity (DTH) response via production of a variety of inflammatory cytokines. While both test systems are still widely used, their sensitivity is highly variable and ranges from 20 to 60% for microscopy 3, 4, and 67 to 80% for skin-testing 5, 6. In patients with HIV infection and other forms of immunosuppression, the sensitivity is even worse and far beyond being adequate for a modern diagnostic test 7, 8. In their recent manuscript, Leidl et al. 9 now compare the performance …