FIG. 3.

Inhibition of lymphocyte proliferation is not mediated by apoptosis but is dependent on IL-2. (A) Apoptosis of mixed lymphocytes was measured by annexin V-propidium iodide staining 5 days post-coculture with allogeneic APCs with medium alone, with TNF-α, with HPIV3, or with influenza virus. Lymphocyte populations were gated, and percentages of early and late apoptotic cells are shown in the lower right quadrant and upper right quadrant, respectively. Results are representative of three experiments. (B) IL-2 levels in the supernatants from cocultures described above. FLU, influenza virus. *, P < 0.05. (C) Lymphocyte proliferation with APCs with medium alone, with APCs plus TNF-α, with APCs plus HPIV3 (PIV), or with HPIV3-infected APCs with IL-2. *, P < 0.05.