FIG. 5.

HIV Tat increases secretion of soluble TRAIL in media of U937 cells and monocytes. For this experiment, 3 × 10⁶ U937 cells (A), human monocytes (B), and CD4⁺ cells (C) in 100 μl of medium were incubated with or without HIV Tat (10 to 1,000 ng/ml) at 37°C for 20 h, and then 20 μl of cell medium was separated by SDS-10% PAGE. Proteins were transferred to nitrocellulose membrane and incubated with polyclonal anti-TRAIL (H-257; 1:1,000). Lanes (from left), 1, no HIV Tat protein; 2 to 5, extracellular media exposed to 10 to 1,000 ng of Tat/ml. TRAIL secretion could not be detected from T-lymphocyte cultures after 20 h.