Relevance of QuantiFERON-TB Gold Plus and Heparin-Binding Hemagglutinin Interferon-γ Release Assays for Monitoring of Pulmonary Tuberculosis Clearance: A Multicentered Study

Abstract

BackgroundTuberculosis (TB) is a leading infectious cause of death. To improve treatment efficacy, quicker monitoring methods are needed. The objective of this study was to monitor the response to a heparin-binding hemagglutinin (HBHA) interferon-γ (IFN-γ) release assay (IGRA) and QuantiFERON-TB Gold Plus (QFT-P) and to analyze plasma IFN-γ levels according to sputum culture conversion and immune cell counts during treatment.MethodsThis multicentered cohort study was based in Bangladesh, Georgia, Lebanon, Madagascar, and Paraguay. Adult, non-immunocompromised patients with culture-confirmed pulmonary TB were included. Patients were followed up at baseline (T0), after two months of treatment (T1), and at the end of therapy (T2). Clinical data and blood samples were collected at each timepoint. Whole blood samples were stimulated with QFT-P antigens or recombinant methylated Mycobacterium tuberculosis HBHA (produced in Mycobacterium smegmatis; rmsHBHA). Plasma IFN-γ levels were then assessed by ELISA.FindingsBetween December 2017 and September 2020, 132 participants completed treatment, including 28 (21.2%) drug-resistant patients. rmsHBHA IFN-γ increased significantly throughout treatment (0.086 IU/ml at T0 vs. 1.03 IU/ml at T2, p < 0.001) while QFT-P IFN-γ remained constant (TB1: 0.53 IU/ml at T0 vs. 0.63 IU/ml at T2, p = 0.13). Patients with low lymphocyte percentages (<14%) or high neutrophil percentages (>79%) at baseline had significantly lower IFN-γ responses to QFT-P and rmsHBHA at T0 and T1. In a small group of slow converters (patients with positive cultures at T1; n = 16), we observed a consistent clinical pattern at baseline (high neutrophil percentages, low lymphocyte percentages and BMI, low TB1, TB2, and MIT IFN-γ responses) and low rmsHBHA IFN-γ at T1 and T2. However, the accuracy of the QFT-P and rmsHBHA IGRAs compared to culture throughout treatment was low (40 and 65% respectively). Combining both tests improved their sensitivity and accuracy (70–80%) but not their specificity (<30%).ConclusionWe showed that QFT-P and rmsHBHA IFN-γ responses were associated with rates of sputum culture conversion. Our results support a growing body of evidence suggesting that rmsHBHA IFN-γ discriminates between the different stages of TB, from active disease to controlled infection. However, further work is needed to confirm the specificity of QFT-P and rmsHBHA IGRAs for treatment monitoring.

In-Depth Immunophenotyping With Mass Cytometry During TB Treatment Reveals New T-Cell Subsets Associated With Culture Conversion

“…We used QFT-P TB2, which elicits cytotoxic CD8 + responses in addition to ESAT-6/CFP-10-induced CD4 + responses ( 25 ), as well as rmsHBHA, a recombinant Mtb protein exposing many different epitopes. The latter was included because the IFN-γ response to HBHA, to which both CD4 + and CD8 + cells participate ( 58 ), is impaired in active TB patients and restored during treatment ( 24 , 59 , 60 ). Here, changes during treatment in CD8 + , CD4 + , DN, and γδ T-cell subsets were detectable within unstimulated and TB2 samples, consistently with previous works ( 25 ).…”

“…For the same reason, the study was conducted on peripheral blood, while the main infectious focus of TB is in the lungs. In addition, since the study required to IGRAs to be performed on the same blood samples prior to cell cryopreservation ( 24 ), we did not perform intracellular cytokine staining. Hence, the integrality of the observed cell phenotype changes may not be associated with Mtb -specific responses.…”

“…Detailed whole blood collection and stimulation processes were described elsewhere ( 24 ). Briefly, at every follow-up visit, 1mL of whole blood was drawn from the antecubital area of the arm and seeded directly into each QuantiFERON-TB Gold Plus (QFT-P, Qiagen) tube and incubated for 24 hours.…”

Longitudinal Variations of M. tuberculosis-Induced IFN-γ Responses in HIV-Negative Pregnant Women Exposed to Tuberculosis

“…Study participants were included from two studies: a cross-sectional prospective cohort study for non-pregnant women and one cohort survey for pregnant women conducted between April 2018 to August 2019 in primary healthcare facilities in the capital city of Antananarivo, Madagascar [as previously described in 11 and Chedid et al., 2012 ( 12 )]. Pregnant women with TB-compatible symptoms defined as one or a combination of cough more than 2 weeks, hemoptysis, dyspnea, chest pain, weight loss, night sweats, loss of appetite, fever, and deterioration of general condition were invited to participate.…”

Multi-country evaluation of RISK6, a 6-gene blood transcriptomic signature, for tuberculosis diagnosis and treatment monitoring

“…However, the combined use of QFT-P with the heparin-binding hemagglutinin antigen; HBHA-based IGRAs, that relies on the stimulation of whole blood with recombinant Mtb HBHA protein expressed in Mycobacterium smegmatis (IGRAs-rmsHBHA) 10 , recently revealed the potential for the stratification of TB stages (e.g. ATB vs LTBI) 11 – 14 .…”