Figure 1.

Expression of CD38, HLADR, and Ki67 on IFN-γ ⁺CD4⁺ T cells distinguishes active from latent tuberculosis (TB). A, Frequencies of CD38⁺, HLADR⁺, and Ki67⁺cells within IFN-γ ⁺ CD4⁺ T cells were examined in peripheral blood mononuclear cells stimulated with ESAT6-CFP10 peptide pools (10 µg/mL) from individuals with latent TB infection (LTBI; n = 50) or active TB (ATB; n = 100). Lines represent median values and interquartile ranges. Data were analyzed using the Mann-Whitney U test. B, Receiver operator characteristic (ROC) curve analyses of the frequency of CD38⁺, HLADR⁺, or Ki67⁺IFN-γ ⁺ CD4⁺ T cells were used to test accuracy to distinguish ATB from LTBI. In (A), dashed lines represent the discrimination thresholds obtained in ROC curve analysis. C, Graphs in (A) were merged. The red, dashed lines represent the discrimination threshold for each marker and show cutoff values of 18%, 60%, and 5% for CD38⁺IFN-γ ⁺, HLADR⁺IFN-γ ⁺, and Ki67⁺IFN-γ ⁺, respectively. Such thresholds were published previously [5]. Abbreviations: AUC, the area under the curve; CI, confidence interval; IFN-γ, interferon gamma; Sens, sensitivity; Spec, specificity.