Increased plasma levels of TRAIL in HIV-1–infected patients. (A) Plasma samples from 107 HIV-1–infected patients and 53 uninfected controls were tested for their soluble TRAIL content by ELISA. Two groups of HIV-1–infected patients were defined depending on their viral load. The mean values of plasma TRAIL were 852 ± 52 pg/mL for 55 control donors, 1339 ± 79 pg/mL for 49 HIV-1–infected patients with undetectable viral load (less than 50 RNA copies per milliliter of blood), and 2242 ± 131 pg/mL for 58 HIV-1–infected patients with higher viral load (more than 50 RNA copies per milliliter of blood). P indicates P values from unpaired t test. Boxes indicate 25th and 75th percentiles, and error bars indicate 10th and 90th percentiles. (B) Longitudinal study of 4 HIV-1–infected patients who, at time 0, began antiretroviral therapy. Patients were followed for 40 weeks. TRAIL level was measure by ELISA. Data are representative of 4 different groups of the 8 patients tested.