-infected individuals according to IFN-γ secretion. A) Distribution of IFN-γ secreting T cells in PBMC of controls (CTR), patients with active TB (TB Act) or individuals with latent TB infection (TB Lat) stimulated for 72 hours with PPD, ESAT-6/CFP-10 or BCG. Horizontal lines indicate the median. Differences between the indicated populations were considered significant when the p-values (indicated by the numbers) were < 0.05. B) ROC curve (on the left) was generated plotting sensitivity (%) versus 100%-specificity% to examine the effect of different cut-points of the percentage of ESAT-6/CFP-10-specific IFN-γ secreting T cells in TB patients, irrespective of disease stage, versus control subjects. Squares indicate the various percentage cut-off values used to calculate the corresponding sensitivity and specificity. Arrow indicates the optimum cut-off (0.1537%) with the best combination of sensitivity and specificity. On the right the AUC and the statistical significance of the ROC curve and the sensitivity and specificity corresponding to the optimum cut-off are indicated.