Increased IDO in PBMCs from HIV⁺ patients impairs T-cell proliferative responses. (A) IDO mRNA expression, measured by real-time quantitative PCR, in PBMCs from HIV⁺ patients who were or were not receiving ART (HIV⁺ ART and HIV⁺ no ART, respectively) and HCs; horizontal bars within boxes correspond to the median; box limits correspond to the 25th and 75th percentiles; vertical lines extend to the 10th and 90th percentiles. (B) Direct correlation between IDO mRNA expression and viral load (log₁₀ copies/mL) in HIV⁺ patients; *= for patients with undetectable viral load a value of 50 copies/mL (detection limit) has been used. (C-D) Proliferative response to PHA (C) and activating antibodies recognizing CD3 and CD28 (D) in PBMCs from HIV⁺ patients and HCs in cultures without (open bars) and with (solid bars) 1-mT; number of viable cells was measured by bioreduction colorimetric assay; relative cell number was calculated for each sample as ratio between stimulated (with PHA or anti-CD3/CD28) and unstimulated culture, in presence or absence of 1-mT; mean values ± SE are shown. (E) The increase of proliferation was calculated as a ratio between proliferative response in presence and in absence of 1-mT; values higher than 1 indicate that proliferation was increased in presence of 1-mT. 1-mT–induced increase in proliferation in HIV⁺ patients receiving ART compared with HIV⁺ patients not receiving ART (no ART); horizontal bars within boxes correspond to the median; box limits correspond to the 25th and 75th percentiles; vertical lines extend to the 10th and 90th percentiles.