The Food and Drug Admin-istration has approved Qiagen’s Quantiferon-TB Gold Plus (QFT-Plus), the fourth generation in the company’s line of blood tests for the detection of latent tuberculosis (TB) infections. The test is a type of interferon-gamma release assay (IGRA), which works by stimulating cells in heparinized whole blood samples with a cocktail of peptides that mimics proteins secreted by Mycobacterium tuberculosis. Cells that have been exposed to TB will release interferon gamma (IFN-g) cytokines in response. The concentration of IFN-g is then measured with an enzyme-linked immunosorbent assay, and further analysis with QFT-Plus analysis software reveals whether the patient has a TB infection. The test has a sensitivity of 95.3% and a specificity of 97.6%.