Diagnosis of tuberculosis infection using interferon-γ-based assays

Area of Science:

• Immunology
• Infectious Diseases
• Diagnostic Medicine

Background:

• Tuberculosis (TB) diagnosis traditionally relies on the tuberculin skin test (TST).
• Interferon-γ release assays (IGRAs) have emerged as a more sensitive and specific alternative for TB infection diagnosis.
• IGRAs include QuantiFERON-TB Gold Intube (QFT-IT) and T-SPOT.TB.

Purpose of the Study:

• To review the clinical utility of IFN-γ release assays (IGRAs) for tuberculosis diagnosis.
• To compare the performance of different IGRA tests (QFT-IT and T-SPOT.TB) against TST.
• To identify limitations and future directions for IGRA development and application.

Main Methods:

• Comparative analysis of Interferon-γ release assays (IGRAs) and tuberculin skin test (TST) based on existing literature.
• Evaluation of diagnostic accuracy, sensitivity, and specificity of IGRAs in various risk groups.
• Review of longitudinal study data on the prognostic value of IGRAs for active TB development.

Main Results:

• IGRAs demonstrate higher accuracy and better correlation with TB risk factors than TST.
• T-SPOT.TB yields more positive results than QFT-IT, but potentially with lower specificity.
• IGRAs maintain better performance than TST in immunocompromised individuals and the very young or old.

Conclusions:

• IGRAs represent a significant advancement over TST for diagnosing latent and active tuberculosis infection.
• While generally superior, IGRA performance can be affected by cellular immunosuppression and extreme age.
• Further research is needed to fully establish the prognostic value of IGRAs and refine their clinical application.