Noclonal antibodies (mAbs) specific for human lymphocytes cell-surface markers, including anti-CD4tricolor (TC), CD8-TC, anti-ab- fluorescein isothiocyanate (FITC), anti-cd-FITC, anti-CD69- phycoerythrin (PE) and antiHLADR-PE (BD Biosciences – San Jose, CA, USA). Following incubation, erythrocytes were lysed using 2 mL of FACS lysing solution (Becton Dickinson Biosciences Pharmingen, San Diego, CA, USA), and cells were washed twice with 2 mL of PBS 0.01 of sodium azide. Cell preparations were Title Loaded From File maintained in 200 mL of FACS fix solution (10 g/L paraformaldehyde, 1 sodium cacodylate, 6.65 g/L sodium chloride) until acquisition in a Becton Dickinson FACS calibur instrument (BD Biosciences – San Jose, CA, USA). At least 35,000-lymphocyte-gated events were acquired for analysis. To determine intra-cellular cytokine expression pattern, PBMC were incubated with anti CD4-TC, anti CD8-TC, anti ab- FITC, anti cd-FITC solutions for 30 min at 4uC. Cells were then washed, fixed, permeabilized with FACS perm buffer (PBS supplemented with 0.5 Bovine Serum Albumin-BSA, 0.5 of saponin and 0.1 sodium azide) and incubated with anti-IFN-c-PE, anti-TNFa-PE and anti-IL-10-PE (BD Biosciences – San Jose, CA, USA) solutions for 30 min at 4uC. Then, the preparations maintained in 200 mL of FACS fix solution until acquisition in a Becton Dickinson FACS calibur instrument.Data analysisLymphocytes were analyzed using the software FlowJo 9.3.2. The analysis of lymphocytes subpopulations was accomplishedRole of CD4-CD8-ab and cd T Cells in TuberculosisRole of CD4-CD8-ab and cd T Cells in TuberculosisFigure 1. High frequencies of DN ab T-cells are associated with TB severity. Representative contour plots showing the gate strategy used for the analysis of CD4 (middle left), CD8 (middle center), DN (middle right) ab-T cells and the expression of CD69 (upper panels) and HLA-DR (lower panels) on DN ab-T cells (A). Percentages of CD4+ (left panels), CD8+ (middle panels) and DN (right panels) ab T-cells in healthy donors (HD, open symbols), TB (total TB, black symbols), nsTB (non-severe TB, light gray symbols) and sTB patients (severe TB, dark gray) were measured before treatment (B). The percentage of CD69 (C) and HLA-DR (D) expression within CD4+ (left panels), CD8+ (middle panels) and DN (right panels) ab T-cells in HD, TB, nsTB and sTB patients were analyzed ex vivo. The boxes represent the means. doi:10.1371/journal.pone.0050923.gaccording to distinct gating strategy as briefly described: following lymphocyte gating on size versus granularity, CD4+ab+, CD8+ab+, CD42CD82ab+, CD4+cd+, CD8+cd+ and CD42CD82cd+ were selected and evaluated according to their frequencies and the expression of activation the markers CD69 and HLA-DR and the production of the intracellular cytokines IFN-c, TNF-a and IL-10 (Fig. 1D and 2D).StatisticsStatistical analysis was performed comparing HD and TB using Mann Whitney test. For comparisons between HD, nsTB and sTB was performed using Kruskal-Wallis variance 1379592 analysis followed by Dunn’s test for multiple comparisons. Analyses were performed using GraphPad Prism 5.01 software package (San Diego, CA, USA). In all cases, significance was Title Loaded From File considered at p#0.05.Results Higher frequencies of CD42CD82 (DN) ab T-cells are associated with TB severityThe proportion of CD4+, CD8+ and CD42CD82 (DN) ab Tcells, gated as described in Fig. 1A, were analyzed and compared among groups. The frequencies of CD4+ and CD8+ ab T-cells were not different between HD a.Noclonal antibodies (mAbs) specific for human lymphocytes cell-surface markers, including anti-CD4tricolor (TC), CD8-TC, anti-ab- fluorescein isothiocyanate (FITC), anti-cd-FITC, anti-CD69- phycoerythrin (PE) and antiHLADR-PE (BD Biosciences – San Jose, CA, USA). Following incubation, erythrocytes were lysed using 2 mL of FACS lysing solution (Becton Dickinson Biosciences Pharmingen, San Diego, CA, USA), and cells were washed twice with 2 mL of PBS 0.01 of sodium azide. Cell preparations were maintained in 200 mL of FACS fix solution (10 g/L paraformaldehyde, 1 sodium cacodylate, 6.65 g/L sodium chloride) until acquisition in a Becton Dickinson FACS calibur instrument (BD Biosciences – San Jose, CA, USA). At least 35,000-lymphocyte-gated events were acquired for analysis. To determine intra-cellular cytokine expression pattern, PBMC were incubated with anti CD4-TC, anti CD8-TC, anti ab- FITC, anti cd-FITC solutions for 30 min at 4uC. Cells were then washed, fixed, permeabilized with FACS perm buffer (PBS supplemented with 0.5 Bovine Serum Albumin-BSA, 0.5 of saponin and 0.1 sodium azide) and incubated with anti-IFN-c-PE, anti-TNFa-PE and anti-IL-10-PE (BD Biosciences – San Jose, CA, USA) solutions for 30 min at 4uC. Then, the preparations maintained in 200 mL of FACS fix solution until acquisition in a Becton Dickinson FACS calibur instrument.Data analysisLymphocytes were analyzed using the software FlowJo 9.3.2. The analysis of lymphocytes subpopulations was accomplishedRole of CD4-CD8-ab and cd T Cells in TuberculosisRole of CD4-CD8-ab and cd T Cells in TuberculosisFigure 1. High frequencies of DN ab T-cells are associated with TB severity. Representative contour plots showing the gate strategy used for the analysis of CD4 (middle left), CD8 (middle center), DN (middle right) ab-T cells and the expression of CD69 (upper panels) and HLA-DR (lower panels) on DN ab-T cells (A). Percentages of CD4+ (left panels), CD8+ (middle panels) and DN (right panels) ab T-cells in healthy donors (HD, open symbols), TB (total TB, black symbols), nsTB (non-severe TB, light gray symbols) and sTB patients (severe TB, dark gray) were measured before treatment (B). The percentage of CD69 (C) and HLA-DR (D) expression within CD4+ (left panels), CD8+ (middle panels) and DN (right panels) ab T-cells in HD, TB, nsTB and sTB patients were analyzed ex vivo. The boxes represent the means. doi:10.1371/journal.pone.0050923.gaccording to distinct gating strategy as briefly described: following lymphocyte gating on size versus granularity, CD4+ab+, CD8+ab+, CD42CD82ab+, CD4+cd+, CD8+cd+ and CD42CD82cd+ were selected and evaluated according to their frequencies and the expression of activation the markers CD69 and HLA-DR and the production of the intracellular cytokines IFN-c, TNF-a and IL-10 (Fig. 1D and 2D).StatisticsStatistical analysis was performed comparing HD and TB using Mann Whitney test. For comparisons between HD, nsTB and sTB was performed using Kruskal-Wallis variance 1379592 analysis followed by Dunn’s test for multiple comparisons. Analyses were performed using GraphPad Prism 5.01 software package (San Diego, CA, USA). In all cases, significance was considered at p#0.05.Results Higher frequencies of CD42CD82 (DN) ab T-cells are associated with TB severityThe proportion of CD4+, CD8+ and CD42CD82 (DN) ab Tcells, gated as described in Fig. 1A, were analyzed and compared among groups. The frequencies of CD4+ and CD8+ ab T-cells were not different between HD a.