Enhancement of Human Antigen-Specific Memory T-Cell Responses by Interleukin-7 May Improve Accuracy in Diagnosing Tuberculosis

University of Texas School of Public Health, Galveston, TX 77555-0567, USA.
Clinical and vaccine Immunology: CVI (Impact Factor: 2.47). 09/2008; 15(10):1616-22. DOI: 10.1128/CVI.00185-08
Source: PubMed


Children and immunocompromised adults are at an increased risk of tuberculosis (TB), but diagnosis is more challenging. Recently
developed gamma interferon (IFN-γ) release assays provide increased sensitivity and specificity for diagnosis of latent TB,
but their use is not FDA approved in immunocompromised or pediatric populations. Both populations have reduced numbers of
T cells, which are major producers of IFN-γ. Interleukin 7 (IL-7), a survival cytokine, stabilizes IFN-γ message and increases
protein production. IL-7 was added to antigen-stimulated lymphocytes to improve IFN-γ responses as measured by enzyme-linked
immunosorbent assay (ELISA) and enzyme-linked immunospot (ELISPOT) assay. Antigens used were tetanus toxoid (n = 10), p24 (from human immunodeficiency virus [HIV], n = 9), and TB peptides (n = 15). Keyhole limpet hemocyanin was used as a negative control, and phytohemagglutinin was the positive control. IL-7 improved
antigen-specific responses to all antigens tested including tetanus toxoid, HIV type 1 p24, and TB peptides (ESAT-6 and CFP-10)
with up to a 14-fold increase (mean = 3.8), as measured by ELISA. Increased IFN-γ responses from controls, HIV-positive patients,
and TB patients were statistically significant, with P values of <0.05, 0.01, and 0.05, respectively. ELISPOT assay results confirmed ELISA findings (P values of <0.01, 0.02, and 0.03, respectively), with a strong correlation between the two tests (R2 = 0.82 to 0.99). Based on average background levels, IL-7 increased detection of IFN-γ by 39% compared to the level with
antigen alone. Increased production of IFN-γ induced by IL-7 improves sensitivity of ELISA and ELISPOT assays for all antigens
tested. Further enhancement of IFN-γ-based assays might improve TB diagnosis in those populations at highest risk for TB.

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Available from: Edward A Graviss
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    • "The goal of this study is to investigate the associations between the expression levels of a selected group of host innate immune response genes in the peripheral blood mononuclear cells (PBMC) of rhesus macaques (pre-and post- MTB infection) and the severity of TB pathogenesis. The selection of the host candidate genes in the present study was based on a comprehensive literature review and includes: PPARG [13], nuclear receptor subfamily 2 group C member 2 (NR2C2) also known as testicular receptor 4 (TR4) [13], IFNE [14] [15] [16], CD40 [17] [18], chemokine C-X-C motif ligand 10 (CXCL10) also known as IFNG-inducible protein 10 (IP10) [19], CSF2 [20] [21], CD40L [22] [23] [24], IL7 [25] [26] [27], IL15 [28] [29], FAS (CD95) [30], IL23A [31] [32], IL12A [33] [34] [35] [36] [24], IL13 [37], IL4 [38] [39] [40] [36], IL5, solute carrier family 11 member 1 (SLC11A1) also known as natural resistance-associated macrophage protein (NRAMP1) [41] [42] [43] [44] [45] [46], TLR2 [47] [48], FASL [49], IL17A [50] [51], CCL2 [52] [53] [54] [55], tumor necrosis factor-α (TNF) [34] [56], nitric oxide synthase 2A (NOS2A) also known as iNOS [57] [58] [10] [59] [60], and dendritic cell-specific intercellular adhesion molecule-3-Grabbing non-integrin (DCSIGN) also known as CD209 [61] [62]. Previous studies involving human subjects, in vivo mouse model experiments, and in vitro cell cultures have shown that the expression of these genes may be associated with TB pathogenesis. "
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    ABSTRACT: Tuberculosis (TB) pathologic lesions in rhesus macaques resemble those in humans. The expression levels of several host TB candidate genes in the peripheral blood mononuclear cells (PBMCs) of six rhesus macaques experimentally infected with Mycobacterium tuberculosis were quantified pre-infection and at several dates post-infection. Quantitative measures of TB histopathology in the lungs including: granuloma count, granuloma size, volume of granulomatous and non-granulomatous lesions, and direct bacterial load, were used as the outcomes of a multi-level Bayesian regression model in which expression levels of host genes at various dates were used as predictors. The results indicate that the expression levels of TR4, CD40, CD40L, FAS (CD95) and TNF in PBMC were associated with quantitative measures of the severity of TB histopathologic lesions in the lungs of the study animals. Moreover, no reliable association between the expression levels of IFNE in PBMCs and the severity of TB lesions in the lungs of the study animals was found. In conclusion, PBMC expression profiles derived from the above-listed host genes might be appropriate biomarkers for probabilistic diagnosis and/or prognosis of TB severity in rhesus macaques.
    Full-text · Article · Oct 2015 · Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases
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    • "One concern relating to the development of lateral flow based tests is the ability to detect markers that are produced in low amounts. It has been shown that cytokine responses can be enhanced by addition of cytokines such as IL-7 [45] and IL-12 [46] into cultures and through the delivery of the antigens using vectors such as the Bordetella pertusis adenylate cyclase vector [47], and other adjuvants [48]. Lateral flow tests using upconverting phospor technology were shown to detect IFN-γ in culture supernatants with sensitivity below 2 pg/ml and were more sensitive than ELISA in detecting Shistosoma circulating antigens [44]. "
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    ABSTRACT: Background Recent interferon gamma (IFN-γ)-based studies have identified novel Mycobacterium tuberculosis (M.tb) infection phase-dependent antigens as diagnostic candidates. In this study, the levels of 11 host markers other than IFN-γ, were evaluated in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens, for the diagnosis of TB disease. Methodology and Principal Findings Five M.tb infection phase-dependent antigens, comprising of three DosR-regulon-encoded proteins (Rv2032, Rv0081, Rv1737c), and two resucitation promoting factors (Rv0867c and Rv2389c), were evaluated in a case-control study with 15 pulmonary TB patients and 15 household contacts that were recruited from a high TB incidence setting in Cape Town, South Africa. After a 7-day whole blood culture, supernatants were harvested and the levels of the host markers evaluated using the Luminex platform. Multiple antigen-specific host markers were identified with promising diagnostic potential. Rv0081-specific levels of IL-12(p40), IP-10, IL-10 and TNF-α were the most promising diagnostic candidates, each ascertaining TB disease with an accuracy of 100%, 95% confidence interval for the area under the receiver operating characteristics plots, (1.0 to 1.0). Conclusions Multiple cytokines other than IFN-γ in whole blood culture supernatants after stimulation with M.tb infection phase-dependent antigens show promise as diagnostic markers for active TB. These preliminary findings should be verified in well-designed diagnostic studies employing short-term culture assays.
    Full-text · Article · Jun 2012 · PLoS ONE
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    • "It may also imply that the worth of testing candidate vaccines based on these antigens needs to be reassessed in certain populations. However, it has been shown that responses to TB antigens could be enhanced if antigens are delivered using vectors such as the Bordetella pertusis adenylate cyclase vector [43], use of other adjuvants [32] or the addition of IL-7 [44] and IL-12 [45] into cultures. It is not known if addition of cytokines might have improved upon the diagnostic ability of the antigens. "
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    ABSTRACT: Confirming tuberculosis (TB) disease in suspects in resource limited settings is challenging and calls for the development of more suitable diagnostic tools. Different Mycobacterium tuberculosis (M.tb) infection phase-dependent antigens may be differentially recognized in infected and diseased individuals and therefore useful as diagnostic tools for differentiating between M.tb infection states. In this study, we assessed the diagnostic potential of 118 different M.tb infection phase-dependent antigens in TB patients and household contacts (HHCs) in a high-burden setting. Antigens were evaluated using the 7-day whole blood culture technique in 23 pulmonary TB patients and in 19 to 21 HHCs (total n = 101), who were recruited from a high-TB incidence community in Cape Town, South Africa. Interferon-gamma (IFN-γ) levels in culture supernatants were determined by ELISA. Eight classical TB vaccine candidate antigens, 51 DosR regulon encoded antigens, 23 TB reactivation antigens, 5 TB resuscitation promoting factors (rpfs), 6 starvation and 24 other stress response-associated TB antigens were evaluated in the study. The most promising antigens for ascertaining active TB were the rpfs (Rv0867c, Rv2389c, Rv2450c, Rv1009 and Rv1884c), with Areas under the receiver operating characteristics curves (AUCs) between 0.72 and 0.80. A combination of M.tb specific ESAT-6/CFP-10 fusion protein, Rv2624c and Rv0867c accurately predicted 73% of the TB patients and 80% of the non-TB cases after cross validation. IFN-γ responses to TB rpfs show promise as TB diagnostic candidates and should be evaluated further for discrimination between M.tb infection states.
    Full-text · Article · Jan 2012 · BMC Infectious Diseases
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