Nuevas técnicas in vitro en el diagnóstico de la infección tuberculosa

The biological therapies based in the anti-tumor necrosis factor-α (TNF) are an effective alternative for the treatment of chronic inflammatory diseases. However, given that anti-TNF-α therapy has been associated with reactivation of latent tuberculosis infection, a previous evaluation of the patients is required in order to avoid their progression to active TB in case of being infected. Tuberculin skin testing (TST) is used to diagnose tuberculosis infection but it has low specificity in patients who have received the BCG vaccine and low sensitivity in patients with altered cell-mediated immunity. In vitro assays based on the detection of interferon-γ (IFN) released by T cells stimulated by specific Mycobacterium tuberculosis antigens have emerged as an option for the diagnosis of tuberculosis infection. The results to date show, that they are a viable alternative to TST thanks to their higher specificity and sensitivity. Although there are some preliminary results indicating that the IFN-γ tests could be used alone, at the moment it seems more prudent to use them in combination with the TST, considering infection when either of them is positive.