Comparison of an ESAT-6/CFP-10 peptide-based enzyme-linked immunospot assay to a tuberculin skin test for screening of a population at moderate risk of contracting tuberculosis

A Pilot TB Screening Model in a U.S. Prison Population Using Tuberculin Skin Test and Interferon Gamma Release Assay Based on Country of Origin

The objective of this study was to compare tuberculosis (TB) screening results before and after implementation of a stratified testing strategy screening pilot study, incorporating interferon gamma release assay (IGRA) and tuberculin skin test (TST), based on country of origin. In 2015, the Washington State Department of Corrections began screening people born outside of the United States for TB with IGRA, while U.S.-born people continued screening by TST. Of 405 (75%) foreign-born men screened with IGRA, 403 had valid test results and IGRA screening positivity was 10.4% (N = 42). In contrast, among 5,940 primarily U.S-born men screened with TST, 24 (0.4%) were positive. Overall positivity was 1.05%, similar to TST-only positivity in 2013 (1.05%) and 2014 (0.85%). Incorporating IGRA screening among foreign-born persons was feasible in this state prison system.

Diagnostic Usefulness of Cytokine and Chemokine Levels in the Cerebrospinal Fluid of Patients with Suspected Tuberculous Meningitis

In this study, we investigated the diagnostic utility of the cytokine profile of the cerebrospinal fluid (CSF) and enzyme-linked immunospot (ELISPOT) assays of patients with suspected tuberculous meningitis (TBM). We prospectively enrolled adult patients with suspected TBM, and CSF specimens were analyzed for 18 cytokines/chemokines and soluble programmed death protein 1 (PD-1) and programmed death ligand 1 (PD-L1). Enzyme-linked immunospot assays were performed on mononuclear cells from the CSF (CSF-MCs) and peripheral blood (PBMCs). A total of 87 patients with meningitis, including 42 TBM-suspected patients and 45 non-TBM patients, were enrolled. Excluding the 32 patients with possible TBM, 10 patients with TBM and 45 patients with non-TBM were finally analyzed. Levels of adenosine deaminase (ADA), interleukin 12 subunit β (IL-12p40), IL-13, macrophage inflammatory protein α (MIP-1α), and soluble PD-1 and PD-L1 in the CSF were significantly higher in the TBM group than in the non-TBM group (P < 0.05). The optimal cutoff values for the sensitivities and specificities of the test methods for diagnosing TBM with small samples of 10 cases of definite or probable TBM were as follows: ADA > 6.95 U/L, 70% and 81%; IL-12p40 > 52.04 pg/mL, 80% and 73%; IL-13 > 0.44 pg/mL, 90% and 47%; MIP-1α > 8.83 pg/mL, 80% and 62%; soluble PD-1 > 35.87 pg/mL, 80% and 63%; soluble PD-L1 > 24.19 pg/mL, 80% and 61%; CSF-MC ELISPOT > 13.5 spots/250,000 CSF-MC, 30% and 91%; and PBMC ELISPOT > 14 spots/250,000 PBMCs, 50% and 78%, respectively. Therefore, CSF IL-12p40, IL-13, MIP-1α, and soluble PD-1 and PD-L1 concentrations appear to be useful adjuncts for diagnosing TBM.

Enhanced IFN-γ, but not IL-2, response to Mycobacterium tuberculosis antigens in HIV/latent TB co-infected patients on long-term HAART

BACKGROUND

HIV-infected individuals with latent TB infection are at increased risk of developing active TB. HAART greatly reduces the incidence rate of TB in HIV-infected patients and reconstitutes Mycobacterium tuberculosis (M. tuberculosis)-specific immune response in the first 12 months of therapy. The durability of the anti-mycobacterial immune restoration after a year of HAART however remains less investigated.

METHOD

A cross-sectional study was conducted to evaluate M. tuberculosis-specific functional immune responses in HIV/latent TB co-infected patients who were on HAART for at least 1.5 up to 9 years as compared to HAART-naïve patients. Three-hundred sixteen HIV-infected patients without active TB were screened by tuberculin skin testing for M. tuberculosis infection and peripheral blood mononuclear cells (PBMCs) were isolated from 61 HIV/latent TB co-infected patients (30 HAART-naïve and 31 HAART-treated). IFN-γ and IL-2 ELISPOT as well as CFSE cell proliferation assays were performed after stimulation with M. tuberculosis antigens PPD and ESAT-6.

RESULT

The median frequency of PPD and ESAT-6 specific IFN-γ secreting cells was significantly higher in the HAART-treated patients as compared to HAART-naïve patients, p = 0.0021 and p = 0.0081 respectively. However, there was no significant difference in the median frequency of IL-2 secreting cells responding to PPD (p = 0.5981) and ESAT-6 (p = 0.3943) antigens between HAART-naïve and-treated groups. Both IFN-γ and IL-2 responses were independent of CD4+ T cell count regardless of the HAART status. Notably, the frequency of PPD and ESAT-6 specific IL-2 secreting cells was positively associated with CD4+ T cell proliferation while inversely correlated with duration of HAART, raising the possibility that M. tuberculosis-specific IL-2 response that promote the antigen-specific CD4+ T cell proliferation diminish with time on antiretroviral therapy in HIV/latent TB co-infected patients.

CONCLUSION

This study shows an increased M. tuberculosis-specific IFN-γ, but not IL-2, response in HIV/latent TB co-infected patients with long-term HAART, consistent with only partial immune restoration. Future studies should, therefore, be done to prospectively define the rate and extent to which functional immune responses to M. tuberculosis are restored after long-term HAART.

Comparison of Three Cellular Immunoassays to Detect Tuberculosis Infection in 876 Healthy Recruits

The currently purified protein derivative (PPD) skin test and 2 interferon (IFN)-γ release assays (IGRAs) were usually used to detect Mycobacterium tuberculosis infection. We try to evaluate the performance of these methods to detect latent tuberculosis infection (LTBI) in this study. Each subject of the 876 recruits (19.05 ± 1.55, 17-24) underwent the PPD test, enzyme-linked immunospot (ELISPOT) assay, and chemiluminescent enzyme immunoassay (CLEIA). The prevalence of LTBI among the participants, as estimated by PPD, ELISPOT, and CLEIA, was 49.89% (437/876), 25.34% (222/876), and 28.77% (252/876), respectively. Of the participants, positive results were noted in 12.79% (112/876) for both ELISPOT and PPD, 19.52% (171/876) for both CLEIA and PPD; 9.82% (86/876) for 2 IGRAs; and 6.62% (58/876) for all 3 methods. Overall, the consistency among the 3 tests was 36.99% (324/876). ELISPOT-positive rate (41.38%) in the recruits with a PPD result ≥20 mm was higher than PPD <20 mm (24.76%; P < 0.05). Increased PPD skin reactions were associated with significantly increased CLEIA-positive rates and IFN-γ levels. Of 307 recruits without the bacillus Calmette-Guérin (BCG) vaccination, 2 IGRA (42.19%)-positive rates in the PPD-positive group were significantly higher than those in the PPD-negative group (28.40% and 23.05%; P < 0.05 and P < 0.01, respectively).There was low correlation and poor consistency among 2 IGRAs and PPD in healthy recruits, but IGRAs may be more accurate screening methods for TB infection in the countries with BCG vaccination.

Diagnostic accuracy of a selected signature gene set that discriminates active pulmonary tuberculosis and other pulmonary diseases

OBJECTIVE

We validated the accuracy of host selected signature gene set using unstimulated whole blood (WB), and peripheral blood mononuclear cells (PBMC) in the diagnosis of tuberculosis (TB).

METHODS

The unstimulated WB and PBMC from 1417 individuals with active pulmonary TB patients, other lung diseases and healthy participants were analyzed using real time polymerase chain reaction (RT-PCR).

RESULTS

The WB cohort test demonstrates that the combination of GBP5 and KLF2 can differentiate active TB versus HC with sensitivity and specificity of 77.8% and 87.1%, respectively; but most importantly active TB versus OD with sensitivity and specificity of 96.1% and 85.2%, respectively. Again during treatment course, the TB score of GBP5 and KLF2, analytes secretion and clinical parameters were found to be associated in disease progression. In the PBMC cohort test, we found that the only and best discriminatory combination was GBP5, DUSP3 and KLF2 inthe active TB versus HC with a sensitivity and specificity of 76.4% and 85.9%, respectively.

CONCLUSIONS

Our study reveals that GBP5 and KLF2 may be useful as a diagnostic tool for active TB, also the two-gene set may serve as surrogate biomarkers for monitoring TB therapy.

Early diagnosis of spinal tuberculosis

Spinal tuberculosis (STB) is a common manifestation of extrapulmonary tuberculosis (TB). STB accounts for around 2% of all cases of TB and around 15% of extrapulmonary TB cases. The World Health Organization has proposed a global strategy and targets for TB prevention, care, and control after 2015. Under this strategy, patients will receive standard care according to the recommendations and guidelines after confirmation of STB diagnosis. However, current recommendations and guidelines focus on disease and medication therapy management, and recommendations for early detection or decision-making algorithms regarding STB are lacking. In this review, we identified five key components for early diagnosis: (1) risk factors for STB; (2) common symptoms/signs of STB; (3) significant neuroradiological findings of STB; (4) significant laboratory findings of STB, including positive interferon-γ release assays and nonpyogenic evidence in initial laboratory data; and (5) significant clinical findings of STB. Individualized consideration for each patient with STB is essential, and we hope that the algorithm established in this review will provide a valuable tool for physicians who encounter cases of STB.

Evaluation of an enzyme-linked immunospot assay for the immunodiagnosis of atypical spinal tuberculosis (atypical clinical presentation/atypical radiographic presentation) in China

Background

Methods

Results

Conclusions

Interferon γ assays in the diagnosis of tuberculosis infection in psoriasis patients who are candidates for biologic therapies

Although there is no doubt that biologic agents are an effective alternative for the treatment of moderate and severe psoriasis, anti-tumor necrosis factor α therapy has been associated with reactivation of latent tuberculosis infection. Tuberculin skin testing (TST) is used to diagnose tuberculosis infection but it has low specificity in patients who have received the Mycobacterium bovis BCG vaccine and low sensitivity in patients with altered cell-mediated immunity. In vitro assays based on the detection of interferon γ released by T cells stimulated by specific Mycobacterium tuberculosis antigens have emerged as an option for the diagnosis of tuberculosis infection. The results to date show that they are a viable alternative to TST thanks to their higher specificity and sensitivity. Furthermore, these assays are also proving to have high negative predictive value, meaning that we might be able to use them without TST in the short to medium term.

Test variability of the QuantiFERON-TB gold in-tube assay in clinical practice

RATIONALE

Although IFN-γ release assays (IGRAs) are widely used to screen for Mycobacterium tuberculosis infection in high-income countries, published data on repeatability are limited.

OBJECTIVES

To determine IGRA repeatability.

METHODS

The study population included consecutive patients referred to The Methodist Hospital (Houston, TX) between August 1, 2010 and July 31, 2011 for latent tuberculosis (TB) infection screening with an IGRA (QuantiFERON-TB Gold In-Tube; Cellestis, Carnegie, Australia). We performed multiple IGRA tests using leftover stimulated plasma according to a prospectively formulated quality control protocol. We analyzed agreement in interpretation of test results classified according to manufacturer-recommended criteria and repeatability of quantitative TB response.

MEASUREMENTS AND MAIN RESULTS

During the study period, 1,086 test results were obtained from 543 subjects. Per the manufacturer's cut-point, the result of the second test was discordant from that of the first in 28 (8%) of 366 patients with valid test results, including 13 with an initial negative result and 15 with an initial positive result. Although agreement between repeat test results was high (κ = 0.84; 95% confidence interval, 0.79-0.90), the normal expected range of within-subject variability in TB response on retesting included differences of ± 0.60 IU/ml for all individuals (coefficient of variation, 14%), and ± 0.24 IU/ml (coefficient of variation, 27%) for individuals whose initial TB response was between 0.25 and 0.80 IU/ml.

CONCLUSIONS

There is substantial variability in TB response when IGRAs are repeated using the same patient sample. IGRA results should be interpreted cautiously when TB response is near interpretation cut-points.

Interferon γ Assays in the Diagnosis of Tuberculosis Infection in Psoriasis Patients Who Are Candidates for Biologic Therapies

Although there is no doubt that biologic agents are an effective alternative for the treatment of moderate and severe psoriasis, anti-tumor necrosis factor α therapy has been associated with reactivation of latent tuberculosis infection. Tuberculin skin testing (TST) is used to diagnose tuberculosis infection but it has low specificity in patients who have received the Mycobacterium bovis BCG vaccine and low sensitivity in patients with altered cell-mediated immunity. In vitro assays based on the detection of interferon γ released by T cells stimulated by specific Mycobacterium tuberculosis antigens have emerged as an option for the diagnosis of tuberculosis infection. The results to date show that they are a viable alternative to TST thanks to their higher specificity and sensitivity. Furthermore, these assays are also proving to have high negative predictive value, meaning that we might be able to use them without TST in the short to medium term.

Clinical evaluation of a homemade enzyme-linked immunospot assay for the diagnosis of active tuberculosis in China

The rapid diagnosis of smear-negative pulmonary tuberculosis (TB) and extrapulmonary TB is a significant problem in clinical practice. We evaluated the usefulness of a homemade enzyme-linked immunospot (ELISPOT) assay for the diagnosis of active TB in China. Seventy-eight healthy volunteers, 60 patients with active TB, and 32 patients with non-TB diseases were evaluated by tuberculin skin test (TST), an ELISPOT assay using a recombinant CFP-10/ESAT-6 fusion protein (rCFP-10/ESAT-6) as a stimulant, and T-SPOT-TB assay. The spot-forming cells (SFC) from 78 healthy subjects containing both PPD-positive and -negative persons was 3.7 ± 6.5. Among 31 diagnosed TB patients, the ELISPOT assay had a sensitivity of 67.7%, compared to a sensitivity of 77.4% for the T-SPOT-TB assay. The ELISPOT assay was more sensitive in smear-positive TB cases (76.9%) than in smear-negative TB cases (61.1%), while T-SPOT-TB had roughly similar sensitivities in smear-positive (76.9%) and smear-negative TB cases (77.8%). The specificity was 90.6% for ELISPOT and 78.1% for T-SPOT-TB among 32 subjects with non-TB diseases. The SFC of TB cases was significantly higher than that of non-TB disease cases, and the SFC of smear-positive TB cases was significantly higher than that of smear-negative TB cases (P < 0.01). We confirmed that the homemade ELISPOT assay appears more specific for the diagnosis of active TB than T-SPOT-TB. ELISPOT assay may be a useful method for the rapid diagnosis of active TB, especially for cases of smear-negative TB.

IFN-gamma-release assays in the management of tuberculosis

New blood tests for TB are now available. One measures the release of IFN-gamma and the other estimates the number of cells secreting IFN-gamma after stimulation with antigens from Mycobacterium tuberculosis. The choice of antigens (esat-6 and cfp-10) is intended to distinguish TB infection from Bacille Calmette-Guerin vaccination. Tests differ in lymphocyte numbers, the use of an additional antigen (TB7.7 - Rv2654) and sensitivity in concurrent HIV infection. Their role in the routine diagnosis of TB is limited. In latent TB infection, the new tests correlate better with exposure to TB. However, the time course of the immune response, the significance of negative tests, conversions from positive to negative and vice versa and their value in predicting who will develop TB are not yet known. Prospective studies of these tests are needed to establish their practical value rather than theoretical role in latent TB infection. Cohorts of both immunocompetent and immunosuppressed subjects who may develop active disease should be examined.

A statistical method was used for the meta-analysis of tests for latent TB in the absence of a gold standard, combining random-effect and latent-class methods to estimate test accuracy

OBJECTIVE

Because of the lack of a gold standard, the diagnostic performance of tests for the detection of latent tuberculosis infection (LTBI) is not known. However, statistical methods can be used to estimate the accuracy from the studies reporting the concordance among the tests.

STUDY DESIGN AND SETTING

We developed a random-effect latent-class model to estimate performance characteristics of three LTBI diagnostic tests: tuberculin skin test (TST, at 10-mm cutoff), QuantiFERON-TB gold (QFG), and TSPOT-TB from the studies evaluating agreement among the tests.

RESULTS

Nineteen studies were included. QFG had a sensitivity of 0.642 (95% confidence interval [CI]: 0.593-0.691) and specificity of 0.996 (95% CI: 0.989-1.000), TSPOT-TB had a sensitivity of 0.500 (95% CI: 0.334-0.666) and specificity of 0.906 (95% CI: 0.882-0.929), and TST had a sensitivity of 0.709 (95% CI: 0.658-0.761) and specificity of 0.683 (95% CI: 0.522-0.844). Results were not sensitive to the inclusion of any single study. When only the three studies that reported on TSPOT were removed, estimates for the other two tests varied minimally.

CONCLUSIONS

Statistical methods can help estimate the accuracy of LTBI tests. Although the specificities were close to their reported values in the literature, the estimates for sensitivities were low; a finding that should be carefully evaluated.

Evidence-based comparison of commercial interferon-gamma release assays for detecting active TB: a metaanalysis

Test accuracy of interferon-gamma release assays (IGRAs) for diagnosing TB differs when using older or precommercial tools and inconsistent diagnostic criteria. This metaanalysis critically appraises studies investigating sensitivity and specificity of the commercial T-Spot.TB and the QuantiFERON-TB Gold In-Tube Assay (QFT-IT) among definitely confirmed TB cases. We searched Medline, EMBASE, and Cochrane bibliographies of relevant articles. Sensitivities, specificities, and indeterminate rates were pooled using a fixed effect model. Sensitivity of the tuberculin skin test (TST) was evaluated in the context of IGRA studies. In addition, the rates of indeterminates of both IGRAs were assessed. The pooled sensitivity of TST was 70% (95% CI, 0.67-0.72) compared with 81% (95% CI, 0.78-0.83) for the QFT-IT and 88% (95% CI, 0.85-0.90) for the T-Spot.TB. Sensitivity increased to 84% (95%CI, 0.81-0.87) and 89% (95% CI, 0.86-0.91) for the QFT-IT and T-Spot.TB, respectively, when restricted to performance in developed countries. In contrast, specificity of the QFT-IT was 99% (95% CI, 0.98-1.00) vs 86% for the T-Spot.TB (95% CI, 0.81-0.90). The pooled rate of indeterminate results was low, 2.1% (95% CI, 0.02-0.023) for the QFT-IT and 3.8% (95% CI, 0.035-0.042) for the T-Spot.TB, increasing to 4.4% (95% CI, 0.039-0.05) and 6.1% (95% CI, 0.052-0.071), respectively, among immunosuppressed hosts. The newest commercial IGRAs are superior, in comparison with the TST, for detecting confirmed active TB disease, especially when performed in developed countries.

Use of T cell-based diagnosis of tuberculosis infection to optimize interpretation of tuberculin skin testing for child tuberculosis contacts

BACKGROUND

Treatment of recent tuberculosis infection in children aged <2 years is essential, because of high risk of progression to disease, but diagnosis is hindered by the inaccuracy of the tuberculin skin test (TST). More-accurate T cell-based tests of infection could enhance diagnosis by optimizing interpretation of the TST results.

METHODS

A total of 979 child tuberculosis contacts in Istanbul underwent the TST and enzyme-linked immunospot assay. Using enzyme-linked immunospot test results as a reference standard, we assessed the effect of age and bacille Calmette-Guérin (BCG) vaccination on the sensitivity and specificity of the TST, and we computed the optimal TST cutoff points, using receiver operating characteristic curves.

RESULTS

With a TST cutoff point of >or=10 mm, the sensitivity of the TST was 66% for children aged <2 years, which was lower than that for older children (P= .006). Specificity was 75% for BCG-vaccinated children, compared with 92% for unvaccinated children (P= .001). Optimal cutoff points improved TST specificity for children with 1 BCG scar, with little loss of sensitivity. Despite the use of optimal cutoff points, TST sensitivity remained <70% for children aged <2 years, specificity remained <87% for BCG-vaccinated children aged >or=2 years, and overall accuracy was low for children with >1 BCG scar.

CONCLUSIONS

Negative results of the TST cannot exclude tuberculosis infection for child tuberculosis contacts aged <2 years, which supports the use of preventive therapy regardless of the TST results for this age group. In children aged >or=2 years, the accuracy of the TST can be improved by adjustment of cutoff points for BCG-vaccinated children but remains poor for children with >1 BCG scar. This methodology can define optimal TST cutoff points for diagnosis of tuberculosis infection tailored to target populations.

T-cell responses to the Mycobacterium tuberculosis-specific antigens in active tuberculosis patients at the beginning, during, and after antituberculosis treatment

The objectives of the study were to assess the performance of the QuantiFERON-TB Gold In-Tube (QFN-G-IT) and the T-SPOT.TB tests in the immunodiagnosis of active tuberculosis (TB) in adult patients, and to study the T-cell interferon gamma (IFN-gamma) responses during treatment and in patients who have recovered after curative treatment and self-healed TB patients. When only analyzing patients included at the beginning of treatment, the sensitivity was 83.3% for T-SPOT.TB and 69.4% for QFN-G-IT. In contrast, when evaluating patients during treatment, the sensitivity of the T-SPOT.TB and QFN-G-IT decreased to 69.8% and 48.8%, respectively. The response to the specific antigens increased after finishing the treatment compared with the values during the treatment. The T-SPOT.TB was more sensitive in diagnosing active TB than the QFN-G-IT. The IFN-gamma tests could be used as a complementary method in the diagnosis of active TB.

Discordant QuantiFERON-TB Gold test results among US healthcare workers with increased risk of latent tuberculosis infection: a problem or solution?

OBJECTIVE

In late 2006, our hospital implemented use of the QuantiFERON-TB Gold (QFT-G) assay, a whole-blood interferon-gamma release assay, for detection of tuberculosis infection. All newly hired healthcare workers (HCWs) with positive Mantoux tuberculin skin test (TST) results were routinely tested with the QFT-G assay, to take advantage of its higher specificity. We then undertook a quality assurance review to evaluate the QFT-G test results in HCWs with multiple risk factors for latent tuberculosis infection (LTBI).

METHODS

The clinical records for TST-positive HCWs tested with the QFT-G assay were reviewed. HCWs with 2 or more risk factors commonly associated with LTBI were classified as "increased risk" (IR). IR HCWs who had negative QFT-G test results underwent repeat QFT-G testing and were offered testing with a different interferon-gamma release assay (T-SPOT.TB) and with extended T cell stimulation assays.

RESULTS

Of 143 TST-positive HCWs tested with the QFT-G assay, 26 (18%) had positive results, 115 (81%) had negative results, and 2 (1%) had indeterminate results. Of 82 IR HCWs, 23 (28%) had positive QFT-G test results, and 57 (70%) had negative results. Of the 57 IR HCWs with negative results, 43 underwent repeat QFT-G testing: 41 had negative results again, and 2 had positive results. These 43 HCWs were also offered additional testing with the T-SPOT.TB diagnostic, and 36 consented: 31/36 tested negative, and 5/36 tested positive. Extended assays using the antigens ESAT-6 and CFP-10 confirmed the positive results detected by the overnight assays and yielded positive results for an additional 7/36 (19%) of individuals; strikingly, all 36 HCWs had strongly positive test results with assays using purified protein derivative.

CONCLUSIONS

The extreme discordance between the results of our clinical diagnostic algorithm and the results of QFT-G testing raises concern about the sensitivity of the QFT-G assay for detection of LTBI in our HCWs. Results of extended stimulation assays suggest that many of our IR HCWs have indeed been sensitized to Mycobacterium tuberculosis. It is possible that the QFT-G assay identifies those at higher reactivation risk rather than all previously infected, but, in the absence of long-term follow-up data, we should interpret negative QFT-G results with some caution.

Confronting the scientific obstacles to global control of tuberculosis

Tuberculosis (TB) is a major threat to global health, recently exacerbated by the emergence of highly drug-resistant forms of the disease-causing pathogen and synergy with HIV/AIDS. In 2006, the Stop TB Partnership published "The global plan to stop TB: 2006--2015," which set out a vision of halving the prevalence of and mortality caused by the disease by 2015, followed by eliminating the disease as a public health problem by 2050. This vision depends on the development of improved diagnostics, simpler treatment, and more effective vaccination. Recently, active translational research pipelines directed toward each of these goals have been established, but improved understanding of the fundamental biology of this complex disease will prove to be the key to radical advances in TB control.

Comparison of two commercially available gamma interferon blood tests for immunodiagnosis of tuberculosis

We evaluated the T-SPOT.TB and Quantiferon-TB Gold In tube (QFN-G-IT) tests for diagnosing Mycobacterium tuberculosis infection. T-SPOT.TB was more sensitive than QFN-G-IT in diagnosing both active and latent infection. Both gamma interferon tests were unaffected by prior Mycobacterium bovis BCG vaccination. Among children who were not BCG vaccinated but had a positive tuberculin skin test, QFN-G-IT was negative in 53.3% of cases, and T-SPOT.TB was negative in 50% of cases.