CD8 response measured by QuantiFERON-TB Gold Plus and tuberculosis disease status

Area of Science:

• Immunology
• Infectious Diseases
• Diagnostics

Background:

• The clinical utility of the QuantiFERON-TB Gold-Plus (QFT-Plus) interferon gamma release assay, which measures CD8 response, requires further investigation.
• Existing interferon gamma release assays primarily focus on CD4 responses, leaving the role of CD8 responses in tuberculosis diagnosis underexplored.

Purpose of the Study:

• To evaluate the performance of the QFT-Plus assay in distinguishing between active tuberculosis (TB), latent tuberculosis infection (LTBI), and uninfected individuals.
• To assess the concordance between QFT-Plus and the established QuantiFERON-TB Gold In-Tube (QFT-GIT) assay.
• To investigate the specific CD8 T-cell responses measured by QFT-Plus in different TB infection states.

Main Methods:

• A prospective study was conducted in Taiwan involving active TB patients, LTBI contacts, and uninfected contacts.
• Participants were tested using both QFT-GIT and QFT-Plus assays.
• LTBI was defined by a positive QFT-GIT result with the exclusion of active TB.

Main Results:

• High concordance (89.3%) was observed between QFT-GIT and QFT-Plus assays.
• While TB1 and TB2 responses did not differ significantly between active TB and LTBI groups, CD8 responses were significantly higher in active TB patients compared to LTBI individuals (p=0.011).
• Culture-confirmed TB cases exhibited higher CD8 responses than LTBI cases (p=0.004).

Conclusions:

• The QFT-Plus assay demonstrates specific CD8 T-cell responses that can differentiate between active TB, LTBI, and uninfected individuals.
• The findings suggest that QFT-Plus has potential clinical applications in TB diagnosis, particularly by leveraging CD8 responses.
• Further research is warranted to fully elucidate the clinical utility of QFT-Plus in various TB epidemiological settings.