Immunologic Diagnosis of Active Tuberculosis

Abstract

Clinically evident active pulmonary or extrapulmonary tuberculosis (TB) does not pose a significant diagnostic chal-lenge, but the diagnosis of subclinical or atypical forms of TB is much more troublesome. More accurate tests that can specifi-cally diagnose active TB have been much awaited. Interferon-γ (IFN-γ) release assays (IGRAs) are recently developed tests recommended for the diagnosis of latent TB, together with the tuberculin skin test (TST), which had for a long time been the only diagnostic tool for this condition [1]. Although the original intent of IGRAs was for the diagnosis of latent TB, the tests have recently become attractive as a possible option in the diagnosis of active TB, as well. IGRAs measure the in vitro cellular immune responses to Mycobacterium tuberculosis-specific antigens, including early secreted antigenic target 6 (ESAT-6) and culture filtrate protei