Evaluation of individual IFN-γ production by prolonged-based incubation assay.

<p>Response to sum of intact recombinant ESAT-6 and CFP-10 proteins after 6 days of stimulation was evaluated in 8 TB patients with QFT-G reversion (positive to negative) during treatment (A), 10 TB patients with persistent QFT-G positive results at the end of therapy (B), and 5 healthy donors (C). The largest increase in IFN-γ production was seen only in TB patients with persistent positive QFT-G results. Statistical significance was analyzed by the Mann–Whitney U-test.</p

IFN-γ concentrations in TB patients according to the results of QFT-G assay at the end of treatment.

<p><b>Group A:</b> TB patients who had a QFT-G reversion (positive to negative) at the end of therapy.</p><p><b>Group B:</b> TB patients who remained QFT-G positive at the end of therapy.</p

Cytofluorimetric analysis of phenotypic profile of T cells from two representative TB patients at the end of treatment.

<p>A representative sample of one TB patient with QFT-G reversion (positive to negative) at the end of therapy (panel A) and one TB patient with persistent QFT-G positive result (panel B) is shown. The percentage of CD4+ and CD8+ T cells that expressed CD45RO and lymphotropic chemokine receptor CCR7 was assessed in diluted whole blood after 6 days of in vitro stimulation with intact recombinant ESAT-6 and CFP-10 proteins. Effector memory (EM) cells (CD45RO+/CCR7−) are shown in the upper left quadrants of both panels; central/memory (CM) cells (CD45RO+/CCR7+) are showed in the upper right quadrants of both panels.</p

IFN-γ responses to mycobacterial antigens, PPD and PHA assessed by short or prolonged incubation-based assays.

<p><b>Abbreviations:</b></p><p>PPD: purified protein derivative; PHA: phytohemagglutinin; rESAT-6: recombinant ESAT-6; rCFP-10: recombinant CFP-10.</p><p><b>Group A:</b> TB patients who had a QFT-G reversion (positive to negative) at the end of therapy.</p><p><b>Group B:</b> TB patients who remained QFT-G positive at the end of therapy.</p

Characteristics of 5 TB subjects with persistent positive IGRA results and less good outcome.

<p><b>Abbreviations:</b></p><p>ND: not done; INH : Isoniazid; RIF: rifampicin.</p

Percentage of CD4+ and CD8+ T cells with effector/memory and central/memory phenotype in 18 TB patients at treatment completion.

<p><b>Abbreviations:</b></p><p><b>T_EM:</b> T cells with an effector/memory phenotype, defined as CD45RO+/CCR7−.</p><p><b>T_CM:</b> T cells with central/memory phenotype, defined as CD45RO+/CCR7+.</p><p><b>Group A:</b> TB patients who had a QFT-G reversion (positive to negative) at the end of therapy.</p><p><b>Group B:</b> TB patients who remained QFT-G positive at the end of therapy.</p

Baseline characteristics of the subjects included in the study.

<p><b>Abbreviations:</b></p><p>BCG: Bacillus Calmette and Guerin; TB: tuberculosis.</p

Effect of antituberculous drugs on IFN-γ release in vitro.

<p>The IFN-γ production was evaluated after overnight incubation with the combination of four drugs (rifampicin, isoniazid, pyrazinamide, ethambutol) at three different concentrations of solution. C1: INH 5 µg/ml, RIF 7 µg/ml, ETB 5 µg/ml, PZA 40 µg/ml; C2: INH 10 µg/ml, RIF 14 µg/ml, ETB 10 µg/ml, PZA 80 µg/ml; C3: INH 15 µg/ml, RIF 21 µg/ml, ETB 15 µg/ml, PZA 120 µg/ml. Controls wells contained only PHA at 5 µg/ml. The concentrations of IFN-γ produced in the presence of drug concentrations compatible with those achieved in the serum of treated patients (C1) were not significantly different from controls containing only PHA (p = 0,071). In contrast, a significant inhibitory effect was found at more elevated drug concentrations (C2 and C3) (p<0.001 for both). Student's t test was used for statistical analysis.</p

Longitudinal changes of specific IFN-γ response in 38 TB patients following anti-tuberculous treatment.

<p>IFN-γ response to sum of ESAT-6 and CFP-10 (overlapping peptides) was measured by QFT-G before, during and at the end of treatment. A significant decrease of IFN-γ response to mycobacterial antigens was found during the therapy (p<0.001, Wilcoxon's signed-rank test). [p: for the comparison of the results at baseline vs. completion of therapy]. Horizontal black line indicates the QFT-G assay cut-off value for a positive result (0.35 UI/mL).</p