Comparison of Two Commercially Available Gamma Interferon Blood Tests for Immunodiagnosis of Tuberculosis

We evaluated the T-SPOT.TB and Quantiferon-TB Gold In tube (QFN-G-IT) tests for diagnosing Mycobacterium tuberculosis infection. T-SPOT.TB was more sensitive than QFN-G-IT in diagnosing both active and latent infection. Both gamma interferon tests were unaffected by prior Mycobacterium bovis BCG vaccination. Among children who were not BCG vaccinated but had a positive tuberculin skin test, QFN-G-IT was negative in 53.3% of cases, and T-SPOT.TB was negative in 50% of cases.