OX40 ligation regulates IL-13 and IFN-γ production at priming. Cells were primed with anti-CD3, anti-OX40 (315) or control mouse IgG2a, and CD32/B7.1 L cells in the presence of anti–IL-4R (5 μg/mL; ▧) or control mouse IgG2a (▧). Cells primed with anti-CD3 and CD32/B7.1 alone (□). Supernatants were collected after 3 days for cytokine measurement. Shown are the mean ± SEM of five experiments. *P < .05; **P < .01.