Serial interferon-gamma release assays during treatment of active tuberculosis in young adults.
BACKGROUND
The role of interferon-γ release assay (IGRA) in monitoring responses to anti-tuberculosis (TB) treatment is not clear. We evaluated the results of the QuantiFERON-TB Gold In-tube (QFT-GIT) assay over time during the anti-TB treatment of adults with no underlying disease.


METHODS
We enrolled soldiers who were newly diagnosed with active TB and admitted to the central referral military hospital in South Korea between May 1, 2008 and September 30, 2009. For each participant, we preformed QFT-GIT assay before treatment (baseline) and at 1, 3, and 6 months after initiating anti-TB medication.


RESULTS
Of 67 eligible patients, 59 (88.1%) completed the study protocol. All participants were males who were human immunodeficiency virus (HIV)-negative and had no chronic diseases. Their median age was 21 years (range, 20-48). Initially, 57 (96.6%) patients had positive QFT-GIT results, and 53 (89.8%), 42 (71.2%), and 39 (66.1%) had positive QFT-GIT results at 1, 3, and 6 months, respectively. The IFN-γ level at baseline was 5.31 ± 5.34 IU/ml, and the levels at 1, 3, and 6 months were 3.95 ± 4.30, 1.82 ± 2.14, and 1.50 ± 2.12 IU/ml, respectively. All patients had clinical and radiologic improvements after treatment and were cured. A lower IFN-γ level, C-reactive protein ≥ 3 mg/dl, and the presence of fever (≥ 38.3°C) at diagnosis were associated with negative reversion of the QFT-GIT assay.


CONCLUSIONS
Although the IFN-γ level measured by QFT-GIT assay decreased after successful anti-TB treatment in most participants, less than half of them exhibited QFT-GIT reversion. Thus, the reversion to negativity of the QFT-GIT assay may not be a good surrogate for treatment response in otherwise healthy young patients with TB.
Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine and Lung Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
Sei Won
SW
Lee
Choon-Taek
CT
Lee
Jae-Joon
JJ
Yim
D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use*; D016903:Drug Monitoring / Q000379:methods*; D005500:Follow-Up Studies; D006801:Humans; D007118:Immunoassay / Q000379:methods; D007371:Interferon-gamma / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D008889:Military Personnel; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification; D013902:Radiography, Thoracic; D056910:Republic of Korea; D014397:Tuberculosis, Pulmonary / Q000188:drug therapy* / Q000276:immunology* / Q000473:pathology; D055815:Young Adult
D000995:Antitubercular Agents; D007371:Interferon-gamma