Effect of IL-12 on IL-15–mediated cytokine production by T cells. (A and B) T cells were isolated by rosetting and then stimulated as indicated. Depicted are the increments in IFN-γ (A) or TNF-α (B) production obtained by stimulation with anti-CD3 + IL-15 (100 ng/mL) over stimulation with anti-CD3 alone of one representative experiment. At total of four experiments have been performed.