Comparative Analysis of Whole-Blood Interferon-c and Flow Cytometry Assays for Detecting Post-treatment Immune Responses in Patients with Active Tuberculosis

Background: Intracellular cytokine flow cytometry (ICCFC) has been explored to detect tuberculosis (TB) infections; however, there are little data regarding its use to examine the dynamic responses of Mycobacterium tuberculosis (MTB)-specific T-cells after anti-tuberculous therapy. The aim of this study was to analyze both dynamic changes in functional MTB antigen-specific T-cell subsets and interferon-gamma (IFN-gamma) levels using ICCFC and the QuantiFERON-TB Gold In-Tube (QFT-IT) test, respectively, following anti-tuberculous treatment in patients with active TB. Methods: Twenty-six patients with active TB were enrolled in the study, and QFT-IT and ICCFC were performed simultaneously both before and after treatment. IFN-gamma levels (QFT-IT test) and the numbers of IFN-gamma- or tumor necrosis factor-alpha (TNF-alpha)-expressing T-cells (ICCFC assay) were examined after stimulation with MTB antigen. Results: There was no significant reduction in the mean IFN-gamma concentrations measured by the QFT-IT test after anti-tuberculous treatment (P = 0.314). ICCFC analysis showed that the numbers of IFN-gamma 1/CD4 T- cells, and CD4(+) T-cells producing TNF-alpha, either alone or in combination with IFN-gamma, were significantly reduced after anti-tuberculous treatment. The IFN-gamma(+)/TNF-alpha(+)/CD4(+) T-cell subset showed the greatest difference between untreated and treated patients with active TB (area under the curve = 0.734, P = 0.004). Conclusions: Unlike the QFT-IT test, ICCFC provides diverse immunological information about dynamic changes in the number of MTB antigen-specific T-cells following anti-tuberculous therapy. Thus, analysis of MTB antigen-stimulated T-cell responses using ICCFC might have a role to play in monitoring treatment responses in patients with active TB. (C) 2013 International Clinical Cytometry Society