IL-7 response of CD4⁺ T cells from tuberculosis patients and healthy contacts.

<p><b>(a)</b> IL-7-induced (10 ng/ml) STAT5 phosphorylation of CD4⁺ T cells from tuberculosis patients (n = 22) and healthy contacts (n = 24) measured by flow cytometry. The STAT5 phosphorylation level of non-stimulated cells has been subtracted of all values. <b>(b)</b> IFNγ/CD40L-expressing CD4⁺ T cells after PPD re-stimulation in the presence or absence of IL-7 detected by flow cytometry. Non-stimulated values with or without IL-7 have been subtracted. <b>(c)</b> Induction of IFNγ/CD40L-expressing CD4⁺ T cells by IL-7 and PPD stimulation. Absolute differences as compared to PPD alone are shown. <b>(d)</b> Plasma IL-6 levels of tuberculosis patients (n = 20) and healthy contacts (n = 24). An arbitrary threshold indicated by a dotted line was set to define tuberculosis patients with high (IL-6_high) and low (IL-6_low) concentrations of plasma IL-6. <b>(e)</b> STAT5 phosphorylation, and IL-7-induced PPD response <b>(f)</b> for tuberculosis patients with high or low plasma IL-6 level, as defined in (d). Median and interquartile range is depicted, and exact Mann-Whitney U test was applied for comparison of groups, whereas paired data was evaluated by Wilcoxon Signed-Rank test. Nominal p-values are indicated as * p < 0.05, ** p < 0.01, *** p < 0.001.