Effect of IL-15 treatment on CNAR by CD8⁺ cells from HIV-infected subjects. (A) CD8⁺ cells from HIV-infected subjects were either treated (control) with 10 U/mL recombinant human IL-2, or treated with IL-12 (1 ng/mL) or with IL-15 (150 ng/mL) for 6 days, and then cocultured with infected CD4⁺ cells at a 0.5:1 ratio. (B) CD8⁺ cells were treated with the indicated concentrations of IL-15. Cells were then removed and cocultured with HIV-1 acutely infected CD4⁺ cells, at a ratio of 0.5:1 in panel A and in panel B (▦) and 1:1 in panel B (▧) (CD8⁺/CD4⁺ cells). Supernatants from duplicate cultures were assayed for RT activity. The extent (percent) of CNAR was determined by comparing these average RT results with the average RT activity from supernatants of duplicate cultures of HIV-infected CD4⁺ cells cultured alone. A bar indicates standard deviation from the average suppression of duplicate cultures. (C) Proliferation of cultured CD8⁺ cells either untreated (10 U/mL IL-2) or treated with the indicated doses of IL-15 was measured on day 5 after a 16-hour incubation with ³ H-thymidine. Results are representative of 5 separate experiments. Error bars indicate SD from the average suppression observed.