FIG. 6.

(A and B) Tat induces cytotoxic activity in monocytes. Human monocytes (effectors) were stimulated with 100 ng of Tat/ml for 24 h and then incubated with chromium-labeled targets, Jurkat (A) or CD4⁺ (B) cells, for a 20-h ⁵¹Cr-release assay. The percentage of specific lysis was observed at several effector-to-target cell (E:T) ratios. The data represent means ± standard errors of the means (SEM) from three independent experiments, each carried out in triplicate. (C) HIV Tat-stimulated human monocytes release functional soluble TRAIL. TSM medium was tested for cytotoxic activity against uninfected Jurkat cells, uninfected primary CD4⁺ cells, HIV-infected Jurkat cells, or infected CD4⁺ cells. These target cells were ⁵¹Cr-labeled and then incubated for 16 h with medium alone, 100 μl of TSM medium, TSMmedium preincubated with anti-TRAIL (N2B2; 100 ng/ml), or TSM medium preincubated with anti-mouse IgG1 (20 μg/ml). Bars represent means ± SEM from three independent experiments, each carried out in triplicate.