Which interferon is used as a diagnostic marker for Mycobacterium tuberculosis infection?

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Last updated: September 14, 2026 • View editorial policy

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Interferon-gamma (IFN-γ) is the interferon used as the diagnostic marker for Mycobacterium tuberculosis infection in interferon-gamma release assays (IGRAs). [1–1–1]

  • What tests measure it:
    • QuantiFERON-TB Gold In-Tube/Plus and T-SPOT.TB detect TB infection by measuring IFN-γ release after stimulation with M. tuberculosis–specific antigens (e.g., ESAT-6, CFP-10) [1–1–1].
  • Why this matters (morbidity, mortality, QOL):
    • Accurate identification of TB infection guides preventive therapy, reducing progression to active TB and thereby lowering morbidity, mortality, and transmission burden.
  • Nuances/pitfalls:
    • IFN-γ indicates immune sensitization; it does not distinguish latent from active TB and is not a “gold standard” on its own—interpret with clinical risk and microbiologic testing when disease is suspected [1–1].
    • Alternative/adjunct markers (e.g., IP-10) are being studied but are not guideline-endorsed replacements for IFN-γ in diagnosis 2.
  • Bottom line for testing:
    • Use an IGRA that measures IFN-γ (e.g., QuantiFERON or T-SPOT.TB) when TB infection testing is indicated, per CDC guidance [1–1–1].

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