Impaired IFN-γ production in tyk2-deficient NK cells on stimulation with IL-12 or IL-18 but not IL-2.

Spleen cells (A,B) or hepatic lymphocytes (C,D) from wild-type or tyk2-deficient mice (Tyk2^−/−) were incubated with IL-15 for 10 days. CD3⁻DX5⁺ NK cells were isolated as shown in the legend to Figure 2 and incubated with medium alone, IL-12, IL-18, or IL-2 (A,C) or the combination of IL-12 and IL-18 (B,D) for 48 hours. The IFN-γ concentration in each supernatant was determined by ELISA.