Two-Hit in vitro T-Cell Stimulation Detects Mycobacterium tuberculosis Infection in QuantiFERON Negative Tuberculosis Patients and Healthy Contacts From Ghana
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Date
2019
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Frontiers In Immunology
Abstract
IFN-γ release assays [e.g., QuantiFERON (QFT)] are widely used for diagnosis of
Mycobacterium tuberculosis (Mtb) infection. T-cell responses against QFT antigens
ESAT6 and CFP10 are highly Mtb specific but previous studies indicated suboptimal
assay sensitivity. Especially for potentially infected healthy contacts (HCs) of tuberculosis
patients, alternative antigen usage and more sensitive tests may contribute to improved
detection of latent Mtb infection. In a pilot case-control study of tuberculosis patients
(n = 22) and HCs (n = 20) from Ghana, we performed multifaceted in vitro assays to
identify optimal assay conditions. This included a two-hit stimulation assay, which is
based on initial and second re-stimulation with the same antigen on d6 and intracellular
IFN-γ analysis, to compare T-cell responses against ESAT6/CFP10 (E6/C10) and
selected latency antigens (i.e. Rv2628, Rv1733, Rv2031, Rv3407) of Mtb. Considerable
subgroups of tuberculosis patients (64%) and HCs (75%) had negative or indeterminate
QFT results partially accompanied by moderate PHA induced responses and high
IFN-γ background values. Intracellular IFN-γ analysis of E6/C10 specific CD4+ T-cell
subpopulations and evaluation of responder frequencies had only moderate effects on
assay sensitivity. However, two-hit in vitro stimulation significantly enhanced E6/C10
specific IFN-γ positive T-cell proportions especially in QFT non-responders, and in both
study groups. Mtb latency antigen-specific T cells against Rv1733 and Rv2628 were
especially detected in HCs after two-hit stimulation and T-cell responses against Rv2628
were highly capable to discriminate tuberculosis patients and HCs. Two-hit in vitro
stimulation may improve moderate sensitivity of short term IFN-γ based assays, like QFT,
to detect Mtb infection. Latency stage-specific antigens added significantly to detection
of Mtb infection in HCs and tuberculosis patients with negative QFT test results
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This article is published by Frontiers in Immunology.
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Citation
Adankwah E, Lundtoft C, Güler A, Franken KLMC, Ottenhoff THM, Mayatepek E, Owusu-Dabo E, Phillips RO, Nausch N and Jacobsen M (2019) Two-Hit in vitro T-Cell Stimulation Detects Mycobacterium tuberculosis Infection in QuantiFERON Negative Tuberculosis Patients and Healthy Contacts From Ghana