New diagnostic tool of tuberculosis: Interferon-gamma assays

New developments have been performed in diagnosis of the tuberculosis (Tbc) which is still the most common and the most mortal preventable infectious disease. Tuberculosis skin test (TST) an immunologic diagnostic method has been used in the diagnosis of Tbc ever since, and is still considered as a gold standart for diagnosis of latent Tbc infection but so far has lost its credibility as a diagnostic test due to its false positivity and negativity characteristics and due to this reason a more sophisticated diagnostic method search is underway. An alternative to the TST has emerged in the form of a new type of invitro T-cell-based assay: The interferon-gamma (IFN-gamma) assay. IFN-gamma assays are based on the principle that T-cells of individuals sensitised with Tbc antigens produce IFN-gamma when they reencounter mycobacterial antigens. In this article the principles leading to the production of IFN-gamma has been reviewed and its usage in real practise has been discussed.