Comparison of a whole-blood interferon-gamma assay and tuberculin skin testing in patients with active tuberculosis and individuals at high or low risk of Mycobacterium tuberculosis infection.

Background: QuantiFeron-TB (QIFN) is a whole-blood interferon-;gamma assay for the recognition of cell-mediated immune response to Mycobacterium tuberculosis infection.

Objectives: To compare the QIFN assay with the tuberculin skin test (TST) in patients with newly diagnosed culture-proven tuberculosis (TB) and healthy volunteers with high or low risk of latent M tuberculosis infection and to identify factors associated with discordance between tests.

Method: Two-hundred fifty-eight subjects underwent both assays.