NK cell activity in tyk2-deficient mice.

Freshly isolated spleen cells were analyzed regarding NK lytic activity against ⁵¹Cr-labeled YAC-1 target cells (A).⁵¹Cr-release in supernatants of cultures at the indicated effector-to-target (E/T) ratios was measured. Spleen cells from wild-type and tyk2^−/− mice were incubated with 2 ng/mL IL-12 (B) or 20 ng/mL IL-18 (C) for 24 hours, and their cytotoxic activity against YAC-1 cells was determined. Freshly isolated hepatic lymphocytes from wild-type or tyk2-deficient mice were analyzed regarding NK lytic activity against ⁵¹Cr-labeled YAC-1 target cells (D). Hepatic lymphocytes from the mutant or wild-type mice were incubated with IL-12 (E) or IL-18 (F) for 24 hours, and their cytotoxic activity against YAC-1 cells was determined.