NK cells reduce proliferation of purified CD3+ T cells from HPIV3-infected cocultures. Purified T cells were cocultured with medium alone, with APCs and NK cells alone or with TNF-α, with HPIV3 (PIV), or with influenza virus (FLU), or T cells were treated with PMA and anti-CD3. Results are representative of two experiments. *, P < 0.05.