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The new QuantiFERON-TB Gold Plus employs modified peptides optimized to elicit an IFNγ response from CD8+ cytotoxic T lymphocytes in addition to CD4+ T cells. With a view to improve the difficult identification of TB cases, we assessed the combination of two specific immunological markers comprising IFNγ secretion and T cells co-expression of CD25 and CD134 in response to Mycobacterium tuberculosis-specific antigens. A total of 34 subjects with suspected TB and 10 age-matched HD were prospectively enrolled. Assessing the performance of QFT-Plus in terms of the TB1 and TB2 results, we found that in TB patients, the quantitative IFNγ value in TB2 was similar to that in TB1, and we did not find any differences irrespective of the disease (pulmonary or extra-pulmonary). The flow cytometric CD25/CD134 assay, allowed a more accurate differentiation between M. tuberculosis-infected and uninfected patients, with a better combination of sensitivity and specificity, especially by evaluation of CD4+ T-cell subset. All individuals with negative QFT-Plus results displayed a positive CD25/CD134 response. Overall, a positive correlation was found between T cells co-expressing CD25/CD134 and IFNγ levels in response to both QFT-Plus TB antigen tubes, as well as between the QFT-Plus TB1 and TB2 tubes. We demonstrated that both TB1 and TB2 induce a higher expression of CD25+CD134+ markers on CD4+ T cells among infected TB subjects, compared to the lower degree of CD8+ T cells, mainly induced to TB2 stimulation. We suggest that a combined use of classic QFT-Plus and specific CD25/CD134 response may be a useful means in the diagnostic workup for active TB. [ABSTRACT FROM AUTHOR]

Discordant results between the interferon-gamma release assays (IGRAs) and tuberculin skin test (TST) are common in latent tuberculosis infection (LTBI). We evaluated whether the measurement of IFN-γ and interleukin (IL)-2T-cell responses, after prolonged Mycobacterium tuberculosis -specific antigen stimulation, can be used as adjunctive biomarker for LTBI detection in subjects with discordant results between TST and QuantiFERON-Gold In-Tube (QFT). 196 healthcare workers were screened for LTBI and in 90 of those participants, the QFT was repeated after 18 h, and IFN-γ/IL-2 immune response was measured after 72 h long-term stimulation. Of the 196 patients, 34 had positive, 155 negative, and 7 indeterminate QFT results. Discordant TST +/QFT − results were found in 29 (14.7%) patients, of whom 6 (20.6%) were Bacillus Calmette–Guerin (BCG) vaccinated. None of 23 non-BCG vaccinated subjects showed a specific IFN-γ immune response after 18 h nor 72 h of incubation, whereas 3/23 (13.04%) discordant subjects produced a specific long-term IL-2 response, which might reflect a LTBI status. In LTBI group (TST +/QFT +) both cytokine levels were increased after long-term in comparison to short-term stimulation. No significant long-term IFN-γ/IL-2 secretion was detected in control group (TST −/QFT −). Taken together, our data showed that the 87% of discordant patients who did not respond to the long-term assay, as controls subjects, were judged LTBI negative. The use of classic QFT and long-term IL-2 response may have a potential role to clarify the LTBI status in individuals in whom the diagnosis of LTBI is uncertain due to the discordance of the available diagnostic tests, such as TST and IGRA. [ABSTRACT FROM AUTHOR]

Background: Dysregulation of host immune responses plays a critical role in the pathogenesis of severe 2009 pandemic H1N1 infection. Whether H1N1 virus could escape innate immune defense in vivo remains to be investigated. The aim of this study was to evaluate the pattern of innate immune response during human 2009 H1N1 infection. We performed the enumeration of circulating myeloid dendritic cells (mDC) and plasmacytoid DC (pDC) in blood from patients with H1N1 pneumonia shortly after the onset of symptoms and during follow-up at different intervals of time. The analysis of CD4 and CD8 count, CD38 T-cell activation marker and serum cytokine/chemokine plasma levels was also done. Methodology/Principal Findings: Blood samples were collected from 13 hospitalized patients with confirmed H1N1-related pneumonia at time of admission and at weeks 1, 4, and 16 of follow-up. 13 healthy donors were enrolled as controls. In the acute phase of the disease, H1N1-infected patients exhibited a significant depletion in both circulating pDC and mDC in conjunction with a decrease of CD4 and CD8 T cell count. In addition, we found plasmatic hyperproduction of IP-10 and RANTES, whereas increase in T-cell immune activation was found at all time points. When we assessed the changes in DC count over time, we observed a progressive normalization of mDC number. On the contrary, H1N1-infected patients did not achieve a complete recovery of pDC count as values remained lower than healthy controls even after 16 weeks of follow-up. Conclusions: H1N1 disease is associated with a profound depletion of DC subsets. The persistence of pDC deficit for several weeks after disease recovery could be due to H1N1 virus itself or to a preexisting impairment of innate immunity. [ABSTRACT FROM AUTHOR]

Background: In recent years, the impact of antituberculous treatment on interferon (IFN)-c response to Mycobacterium tuberculosis antigens has been widely investigated, but the results have been controversial. The objective of the present study was: i) to evaluate longitudinal changes of IFN-c response to M. tuberculosis-specific antigens in TB patients during antituberculous treatment by using the QuantiFERON-TB Gold (QFT-G) assay; ii) to compare the differences in T-cell response after a short or prolonged period of stimulation with mycobacterial antigens; iii) to assess the CD4+ and CD8+ T cells with effector/memory and central/memory phenotype; iv) to investigate the direct in vitro effects of antituberculous drugs on the secretion of IFN-γ. Principal Findings: 38 TB patients was evaluated at baseline and at month 2 and 4 of treatment and at month 6 (treatment completion). 27 (71%) patients had a QFT-G reversion (positive to negative) at the end of therapy, while 11 (29%) TB patients remained QFT-G positive at the end of therapy. Among the 11 patients with persistent positive QFT-G results, six had a complete response to the treatment, while the remaining 5 patients did not have a resolution of the disease. All 27 patients who became QFT-G negative had a complete clinical and microbiological recovery of the TB disease. In these patients the release of IFN-γ is absent even after a prolonged 6-day incubation with both ESAT-6 and CFP-10 antigens and the percentage of effector/memory T-cells phenotype was markedly lower than subjects with persistent positive QFT-G results. The in vitro study showed that antituberculous drugs did not exert any inhibitory effect on IFN-α production within the range of therapeutically achievable concentrations. Conclusions: The present study suggests that the decrease in the M. tuberculosis-specific T cells responses following successful anti-TB therapy may have a clinical value as a supplemental tool for the monitoring of the efficacy of pharmacologic intervention for active TB. In addition, the antituberculous drugs do not have any direct down-regulatory effect on the specific IFN-γ response. [ABSTRACT FROM AUTHOR]