Figure 2. Depletion of regulatory T cells (Treg) enhances activity of interleukin-2 (IL-2) activated natural killer (NK)/lymphokine-activated killer cells.

(a) Nontumor-bearing C57Bl/6 mice were treated as described for Figure 1a, with the addition of an intraperitoneal injection of PC61 24 hours before the first intraperitoneal injection of IL-2 or phosphate-buffered saline (PBS). An additional group of mice received an injection of the NK cell-depleting asialo GM-1 antibody 24 hours before treatment with PC61 and then IL-2. Forty-eight hours after the final injection of IL-2 or PBS, vascular leakage into the lungs was measured. The results shown are from two separate experiments per treatment. (b) Splenocytes were recovered from mice treated as in a, and were plated with YAC cells (1 splenocyte effector:1 YAC target cell) in triplicate wells. After 48 hours, the surviving cells were counted and the result is expressed as a percentage of the controls (YAC + splenocytes from PBS-treated mice). (c) Splenocytes were recovered from mice treated as in a, and were plated with YAC cells (1:1). After 48 hours, the supernatants were assayed for interferon-γ (IFN-γ) using enzyme-linked immunosorbent assay (ELISA). (d) Splenocytes from the same samples as in c were also plated with B16 targets (1:1), and 48 hours later the supernatants were assayed for IFN-γ using ELISA. The results are representative of two separate experiments.