We performed a ROC analysis, and a cut-off >0.45% for activated CD4+ T cells was found as the value allowing the best combination of sensitivity (94.44%, 95% CI 72.2–99.8%) and specificity (100%, 95% CI 69.15–100%; AUC 0.9722; 95% CI 0.9141–1.030%, P < 0.0001) to differentiate Mtb-infected patients (active TB and LTBI) from healthy controls [10]. The gene discussed is CD4; the disease is tuberculosis.