[Up-to-date applicability of interferon-γ release assays for the diagnosis of tuberculosis]

Utility of the in-vitro immunodiagnostic methods, based on the detection of interferon-γ released by T-cells after specific Mycobacterium tuberculosis antigen stimulation (IGRA), has been an improvement in the accuracy of the latent tuberculosis infection diagnosis. IGRA have a well-known higher specificity than the tuberculin skin testing (TST). Moreover, they can obtain a larger number of positive results than the TST in immunocompromised patients. IGRA have shown a high correlation with M. tuberculosis exposure, but their positive and negative predictive value are similar than those obtained by TST. Nevertheless, given their high specificity, they allow reducing number of unnecessary preventive treatments. In addition, these in-vitro techniques are less affected than TST by the different immunosuppressing status. In this review is discussed up-to-date applicability of IGRA in different patient groups: contact studies, pediatric population, immunosuppressed patients, health care workers and active tuberculosis patients. Furthermore, it has been included possible future directions for latent tuberculosis infection and active tuberculosis diagnosis.