TB-IGRA diagnostic test, also referred to as Interferon Gamma Release Assay, is an ELISA for quantitative detection of Interferon Gamma (IFN-γ) that responds to in vitro stimulation by Mycobacterium Tuberculosis antigens in human blood samples. TB-IGRA measures a person’s immune reactivity to Mycobacterium Tuberculosis. The test is intended for use as an aid in the diagnosis of TB infection including both latent Tuberculosis infection and Tuberculosis disease. The immune response caused by Mycobacterium tuberculosis is predominantly a cellular response. After infection with Mycobacterium tuberculosis, the body produces specific memory T cells that circulate in the peripheral blood. The measurement of IFN-γ against Mycobacterium tuberculosis has been shown to be an effective technique for detecting TB infection (both latent and active), called IFN-γ in vitro release assay (IGRA). The major difference from the tuberculin test (TST) is that IGRA selects specific antigens that are present only in Mycobacterium tuberculosis but are absent in BCG and most non-tuberculous mycobacteria.
