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T-cell responses to the Mycobacterium tuberculosis-specific antigen ESAT-6 in Brazilian tuberculosis patients.

Abstract

The Mycobacterium tuberculosis-specific ESAT-6 antigen induces highly potent T-cell responses and production of gamma interferon (IFN-gamma), which play a critical role in protective cell-mediated immunity against tuberculosis (TB). In the present study, IFN-gamma secretion by peripheral blood mononuclear cells (PBMCs) in response to M. tuberculosis ESAT-6 in Brazilian TB patients was investigated in relation to clinical disease types, such as pleurisy and cavitary pulmonary TB. Leprosy patients, patients with pulmonary diseases other than TB, and healthy donors were assayed as control groups. Sixty percent of the TB patients indeed recognized M. tuberculosis ESAT-6, as did 50% of the leprosy patients and 60% of the non-TB controls. Nevertheless, the levels of IFN-gamma in response to the antigen ESAT, but not to antigen 85B (Ag85B) and purified protein derivative (PPD), were significantly lower in controls than in patients with treated TB or pleural or cavitary TB. Moreover, according to Mycobacterium bovis BCG vaccination status, only 59% of the vaccinated TB patients responded to ESAT in vitro, whereas 100% of them responded to PPD. Both CD4 and CD8 T cells were able to release IFN-gamma in response to ESAT. The present data demonstrate the specificity of ESAT-6 of M. tuberculosis and its ability to discriminate TB patients from controls, including leprosy patients. However, to obtain specificity, it is necessary to include quantitative IFN-gamma production in response to the antigen as well, and this might limit the use of ESAT-6-based immunodiagnosis of M. tuberculosis infection in an area of TB endemicity.

More information

Type
Journal Article
Author
Cardoso FL L
Antas PR Z
Milagres AS
Geluk A
Franken KL M C
Oliveira EB
Teixeira HC
Nogueira SA
Sarno EN
Klatser P
Ottenhoff TH M
Sampaio EP
Year of Publication
2002
Journal
Infection and immunity
Volume
70
Issue
12
Number of Pages
6707-14
Date Published
2002 Dec
Language
eng
ISSN Number
0019-9567
Call Number
CARDOSO2002
DOI
10.1128/iai.70.12.6707-6714.2002
Alternate Journal
Infect. Immun.
Publication Language
eng