In vitro hyporesponsiveness of NK cells from Itgb2^Jkr/Jkr mice. NK cells from WT (open histograms) or Itgb2^Jkr/Jkr (black histograms) mice were purified from the spleen and tested for their responsiveness ex vivo. NK-cell degranulation (CD107a exposure) and IFN-γ production were tested by flow cytometry after surface and intracellular stainings, respectively. (A-B) Purified NK cells were activated by antibody-coated plates using anti-NK1.1, anti-NKp46, and anti-Ly49D antibodies or a mixture of the respective isotype controls (IC) for 4 hours. (C) NK cells were incubated with IL-12 or a mixture of IL-12 and IL-18 for 4 hours. Results are expressed as the percentage of NK cells (NK1.1⁺CD3⁻ or NKp46⁺ cells) expressing CD107a or intracellular IFN-γ. Data represent means ± SEM. Statistical analysis was performed using a one-tailed Mann-Whitney test.