IGRAs work by leveraging the immune system's ability to recognize specific antigens. When T-cells in the blood are exposed to antigens specific to Mycobacterium tuberculosis, they release IFN-γ. The amount of IFN-γ released is measured to determine whether the person has been infected with TB. The test is highly specific because it uses antigens that are not present in the BCG vaccine or most non-tuberculous mycobacteria, reducing the risk of false-positive results.
