Sensitivity Analysis and Potential Uses of a Novel Gamma Interferon Release Assay for Diagnosis of Tuberculosis

Sputum smears for acid-fast bacilli (AFB) are the primary methods for diagnosis of tuberculosis (TB) in many countries. The tuberculin skin test (TST) is the primary method for diagnosis of latent TB infection (LTBI) worldwide. The poor sensitivity of the former and the poor specificity of the latter warrant the development of new tests and strategies to enhance diagnostic capabilities. We evaluated the sensitivity of an “in-tube” gamma interferon release assay (IGRA) using TB-specific antigens in comparison to the TST and the sputum smear for AFB in TB cases in South Africa. The sensitivity of the IGRA for TB was considered a surrogate of sensitivity in LTBI. Among 154 patients with a positive culture for Mycobacterium tuberculosis, the sensitivity of the IGRA for the diagnosis of TB varied by clinical subgroup from 64% to 82%, that of the TST varied from 85% to 94%, and that of two sputum smears for AFB varied from 35% to 53%. The sensitivity of the IGRA in human immunodeficiency virus (HIV)-infected TB cases was 81%. HIV-infected TB patients were significantly more likely to have indeterminate IGRA results and produced quantitatively less gamma interferon in response to TB-specific antigens than HIV-negative TB patients. The overall sensitivity of the TST in all TB cases was higher than that of the IGRA (90% versus 76%, respectively). The combined sensitivities of the TST plus IGRA and TST plus a single sputum smear were 96% and 93%, respectively. The TST combined with IGRA or with a single sputum smear may have a role in excluding the diagnosis of TB in some settings

Epigallocatechin-3-gallate induces mesothelioma cell death via H2O2-dependent T-type Ca2+ channel opening

Malignant mesothelioma (MMe) is a highly aggressive, lethal tumour requiring the development of more effective therapies. The green tea polyphenol epigallocathechin-3-gallate (EGCG) inhibits the growth of many types of cancer cells. We found that EGCG is selectively cytotoxic to MMe cells with respect to normal mesothelial cells. MMe cell viability was inhibited by predominant induction of apoptosis at lower doses and necrosis at higher doses. EGCG elicited H2O2release in cell cultures, and exogenous catalase (CAT) abrogated EGCG-induced cytotoxicity, apoptosis and necrosis. Confocal imaging of fluo 3-loaded, EGCG-exposed MMe cells showed significant [Ca2+]irise, prevented by CAT, dithiothreitol or the T-type Ca2+channel blockers mibefradil and NiCl2. Cell loading with dihydrorhodamine 123 revealed EGCG-induced ROS production, prevented by CAT, mibefradil or the Ca2+chelator BAPTA-AM. Direct exposure of cells to H2O2produced similar effects on Ca2+and ROS, and these effects were prevented by the same inhibitors. Sensitivity of REN cells to EGCG was correlated with higher expression of Cav3.2 T-type Ca2+channels in these cells, compared to normal mesothelium. Also, Cav3.2 siRNA on MMe cells reduced in vitro EGCG cytotoxicity and abated apoptosis and necrosis. Intriguingly, Cav3.2 expression was observed in malignant pleural mesothelioma biopsies from patients, but not in normal pleura. In conclusion, data showed the expression of T-type Ca2+channels in MMe tissue and their role in EGCG selective cytotoxicity to MMe cells, suggesting the possible use of these channels as a novel MMe pharmacological target. \ua9 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd

Tuberculosis and HIV–Needed: A New Paradigm for the Control and Management of Linked Epidemics

Tuberculosis (TB) and human immunodeficiency virus (HIV) disease have been closely entwined since the early years of the HIV/AIDS pandemic. The 2 conditions overlap in their epidemiologic characteristics and clinical manifestations and are both clothed in stigma. They individually carry the risk of creating social, economic, and political instability, which is markedly worsened when they affect a region in concert. The overwhelming burden of disease due to both TB and HIV is borne by resource-limited countries and the hardest hit among these are in sub-Saharan Africa. In sub-Saharan Africa, the HIV epidemic is accelerating what was already a massive TB epidemic, with the incidence rate of TB increasing from 146 per 100,000 in 1990 to 345 per 100,000 in 2003. Each disease contributes to the morbidity and mortality of the other. TB is now the leading cause of death among persons with HIV disease. HIV increases the risk of reactivation of latent TB infection (LTBI) and progression to active TB disease more than any other known risk factor. In some countries, the percentage of patients with active TB who are coinfected with HIV is now greater than 60%. Even with appropriate management of TB, patients with HIV co-infection have increased mortality as a consequence of HIV-related complications

Comparing interferon-gamma release assays to tuberculin skin test in Thai children with tuberculosis exposure.

Data on the performance of interferon-gamma release assays (IGRAs), QuantiFERON TB Gold In-tube (QFNGIT) and T-Spot.TB, in diagnosing tuberculosis (TB) are limited in Southeast Asia. This study aims to compare the performances of the two IGRAs and TST in Thai children with recent TB exposure.This multicenter, prospective study enrolled children with recent exposure to active TB adults. Children were investigated for active TB. TST was performed and blood collected for T-Spot.TB and QFNGIT.158 children were enrolled (87% TB-exposed and 13% active TB, mean age 7.2 years). Only 3 children had HIV infection. 66.7% had TST≥10 mm, while 38.6% had TST≥15 mm. 32.5% had positive QFNGIT; 29.9% had positive T-Spot.TB. QFNGIT and T-Spot.TB positivity was higher among children with active TB compared with TB-exposed children. No indeterminate IGRA results were detected. No statistically significant differences between the performances of the IGRAs and TST at the two cut-offs with increasing TB exposure were detected. Concordance for positive IGRAs and TST ranged from 42-46% for TST≥10 mm and 62-67% for TST≥15 mm. On multivariable analyses, exposure to household primary/secondary caregiver with TB was associated with positive QFNGIT. Higher TB contact score and active TB were associated with positive T-Spot.TB.Both QFNGIT and T-Spot.TB performed well in our Thai pediatric study population. No differences in the performances between tests with increasing TB exposure were found. Due to accessibility and low cost, using TST may more ideal than IGRAs in diagnosing latent and active TB in healthy children in Thailand and other similar settings

Correlation of Tests for <i>M. tuberculosis</i> with Graded Exposure to Tuberculosis.

<p>Correlation of Tests for <i>M. tuberculosis</i> with Graded Exposure to Tuberculosis.</p

Baseline Characteristics, TST, and IGRA Results of Thai Pediatric Cohort, N = 158.

†<p>Fisher’s exact.</p><p>NA: not applicable AFB: acid fast bacilli.</p><p>IGRA: Interferon gamma release assays QFNGIT: QuantiFERON Gold In-Tube.</p><p>*HIV testing was not offered because of lack of history of parental HIV infection and clinical signs/symptoms consistent with HIV infection.</p

Association between Tests for <i>M. tuberculosis</i> and Graded Exposure to Tuberculosis.

<p>Association between Tests for <i>M. tuberculosis</i> and Graded Exposure to Tuberculosis.</p