Requirement of tyk2 for up-regulation of NK lytic activity by IL-12 or IL-18.

Spleen cells or hepatic lymphocytes from wild-type or tyk2-deficient mice were incubated with IL-15 for 10 days. CD3⁻DX5⁺ NK cells were isolated by MACS. The expressions of CD3 and DX5 were determined by flow cytometry (A). CD3⁻DX5⁺ NK cells were incubated with IL-12 (2 ng/mL), IL-18 (20 ng/mL), or IL-2 (500 U/mL) for 24 hours, and their cytotoxicity against YAC-1 was determined (B).