Figure 1.

A, B, Plasma indoleamine 2, 3-dioxygenase (IDO) activity in patients with human immunodeficiency virus (HIV) infection in whom active tuberculosis disease developed (A) and in HIV-infected controls (B). IDO activity showed elevation from 6 months before tuberculosis diagnosis (−6 mo). At the time of tuberculosis diagnosis (TBdx), all patients with tuberculosis had IDO activity value >0.80 (red dotted line), compared with 1.5% of controls. Kyn, kynurenine; Trp, tryptophan; V1 (etc), visit 1 (etc). C, Plasma IDO activity as a measure of Kyn/Trp ratio in HIV-infected patients with tuberculosis compared with HIV-infected controls. IDO activity was significantly elevated both at tuberculosis diagnosis and 6 months earlier. D, E, Plasma IDO activity plotted as fold change in patients with tuberculosis (D) and controls (E), showing median and interquartile ranges at each time point (lower and upper portions of boxes represent 25th and 75th percentiles, respectively; horizontal lines within box plots, medians). P values were determined using Kruskal-Wallis tests with Dunn posttests. For patients with tuberculosis, there were 25, 26, 32, 27, and 21 patients, respectively, at the 5 time points shown; for controls, 55, 62, 70, 59, and 33 patients, respectively.