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Combining interferon-γ release assays with lymphocyte enumeration for diagnosis of Mycobacterium tuberculosis
Dingfeng Lv1, Yanqing Liu1, Fei Guo1
1Department of Clinical Laboratory Medicine, Ningbo City First Hospital, Ningbo, Zhejiang, China.
Insights
This study explored combining tuberculosis (TB)-interferon gamma release assays (IGRAs) with lymphocyte counts for diagnosing Mycobacterium tuberculosis infection. The combined approach proved effective for early-stage TB detection.
Area of Science:
- Immunology
- Infectious Diseases
- Diagnostic Medicine
Background:
- Tuberculosis (TB) diagnosis relies on various methods, with interferon-gamma release assays (IGRAs) showing promise.
- Lymphocyte enumeration is a standard hematological parameter.
- Investigating synergistic diagnostic approaches for Mycobacterium tuberculosis infection is crucial.
Purpose of the Study:
- To evaluate the combined diagnostic utility of TB-interferon gamma release assays (IGRAs) and lymphocyte enumeration.
- To assess the effectiveness of this combined approach for diagnosing Mycobacterium tuberculosis infection, particularly in early stages.
Main Methods:
- A retrospective study involving 166 TB patients and 377 non-TB patients was conducted.
- Diagnostic performance was assessed using receiver operating characteristic (ROC) curves and Youden's index.
- Interferon-gamma (IFN-γ) release levels were measured and correlated with lymphocyte counts.
Main Results:
- IFN-γ release was significantly higher in TB patients (pulmonary and extra-pulmonary) compared to non-TB individuals.
- A positive correlation was observed between IFN-γ release and lymphocyte counts/percentages in TB patients.
- The TB-IGRA demonstrated an area under the ROC curve of 0.884, with optimal cut-off yielding 88.6% sensitivity and 77.5% specificity.
Conclusions:
- The combination of TB-interferon gamma release assays (IGRAs) with lymphocyte enumeration is an effective strategy.
- This integrated method aids in the diagnosis of early-stage Mycobacterium tuberculosis infection.
- Further validation may enhance its clinical application in TB diagnostics.
Objective:
To investigate the possibility of combining tuberculosis (TB)-interferon (IFN)-γ release assays (IGRAs) with lymphocyte enumeration for diagnosis of Mycobacterium tuberculosis infection.
Methods:
We performed a retrospective study of 166 TB patients [68 patients with pulmonary tuberculosis TB (PTB) and 98 patients with extra-pulmonary TB (EPTB)] diagnosed in our hospital between January 2016 and May 2018 along with 377 non-TB patients. The diagnostic performance of the TB-IGRA was evaluated using receiver operating characteristic (ROC) curves. Youden's index was used to determine the optimal cut-off threshold.
Results:
IFN-γ release in patients with PTB and EPTB were dramatically higher compared with non-TB patients (203.58±18.00 pg/mL, 201.83±14.56 pg/mL and 32.12±4.36 pg/mL, respectively). IFN-γ release was positively correlated with lymphocyte counts and percentages in patients with PTB (r = 0.252 and r = 0.278, respectively) and EPTB (r = 0.229 and r = 0.298, respectively). No correlation was observed in non-TB patients. The area under the ROC curve for TB-IGRA was 0.884. When the optimal cut-off value for IFN-γ (14 pg/mL, Youden's index 0.661) was applied, the sensitivity was 88.6% and the specificity was 77.5%.
Conclusions:
Combining TB-IGRA with lymphocyte enumeration was effective for diagnosis of early-stage Mycobacterium tuberculosis infection.
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