QuantiFERON-TB Gold Plus (QFT-Plus) differs from the older QuantiFERON-TB Gold In-Tube (QFT-GIT) in that QFT-Plus additionally measures:
- A CD8+ T-cell responses via a second antigen tube (TB2) in addition to CD4+ responses ✓
- B CD4+ T-cell responses to ESAT-6 and CFP-10 (TB1 tube)
- C Antibody titres against PPD
- D IFN-gamma responses to M. bovis BCG antigens
Correct answer: A. CD8+ T-cell responses via a second antigen tube (TB2) in addition to CD4+ responses
Explanation
QFT-Plus adds a second antigen tube (TB2) containing peptides that stimulate both CD4+ and CD8+ T-cell IFN-gamma responses, whereas QFT-GIT's TB antigen tube primarily stimulates CD4+ responses. This CD8+ component may improve sensitivity in immunocompromised patients where CD4 counts are depleted. Both versions exclude BCG cross-reactivity since ESAT-6 and CFP-10 are absent from BCG and most non-tuberculous mycobacteria. The assay measures IFN-gamma release, not antibody titres.
Reference: Ananthanarayan & Paniker's Textbook of Microbiology, 11th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.