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Journal of Immunology Research
Volume 2016, Article ID 7249369, 9 pages
http://dx.doi.org/10.1155/2016/7249369
Research Article

Antigen-Specific IFN-γ Responses Correlate with the Activity of M. tuberculosis Infection but Are Not Associated with the Severity of Tuberculosis Disease

1Department of Immunology, Central Tuberculosis Research Institute, Yauza Alley 2, Moscow 107564, Russia
2Phthisiology Department, Central Tuberculosis Research Institute, Yauza Alley 2, Moscow 107564, Russia
3Department of Microbiology, Central Tuberculosis Research Institute, Yauza Alley 2, Moscow 107564, Russia

Received 3 June 2016; Revised 9 September 2016; Accepted 21 September 2016

Academic Editor: Frederick D. Quinn

Copyright © 2016 Irina Yu. Nikitina et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

IFN-γ is a key cytokine in antituberculosis (TB) defense. However, how the levels of its secretion affect M. tuberculosis (Mtb) infection is not clear. We have analyzed associations between IFN-γ responses measured in QuantiFERON®-TB Gold In-tube (QFT) assay, TB disease severity, and Mtb infection activity. TB severity was evaluated based on the results of radiological, microbiological, and clinical examinations. Antigen-driven IFN-γ secretion did not correlate with TB severity. Mitogen-induced IFN-γ secretion correlated inversely with the form of pulmonary pathology and the area of affected pulmonary tissue; the levels of spontaneous IFN-γ secretion correlated with patients’ age ( = 0.395, = 0.001). Mtb infection activity was evaluated based on radiological data of lung tissue infiltration, destruction, dissemination or calcification, and condensation. The rate of positive QFT results and the levels of antigen-driven IFN-γ secretion increased in a row: patients with residual TB lesions < patients with low TB activity < patients with high TB activity. Thus, antigen-driven IFN-γ secretion and QFT results did not associate with TB severity but associated with the infection activity. The results suggest that quantitative parameters of IFN-γ secretion play a minor role in determining the course of TB disease but mirror the activity of the infectious process.