Impaired NK-cell function in pearl mice.C57BL/6, pearl, and PKO mice were injected intraperitoneally with 200 µg of poly (I:C). At 24 hours later, spleen cells were restimulated for 2 hours with YAC-1 target cells or medium as a control in the presence of anti-CD107a antibody (A-B). (A) Representative histograms of NK1.1⁺CD3⁻ NK cells are shown. Dashed line indicates medium control; solid line indicates restimulation with YAC-1 cells. (B) Degranulation is shown as increase of CD107a expression on NK1.1⁺CD3^- cells (ΔCD107a) after restimulation with YAC-1 cells compared with medium control. (C) NK-cell cytotoxicity was determined in a 5-hour ⁵¹chromium release assay on YAC-1 target cells. Quantification of NK cells was performed by flow cytometry. Representative data for 3 independent experiments with 3-5 mice/group are shown.