Representation and phenotypic characterization of NK cells. (A) Numbers of NK1.1⁺ CD3⁻ cells from the indicated organs from C57BL/6, IK^+/+ Rag^−/−, or IK^L/L Rag^−/− mice. Each dot represents results from individual mice, and bars represent the mean. *P < .05. ***P < .001. (B) CD11b and CD27 expression on NK1.1⁺ CD3⁻ cells from the spleens of the indicated mouse strains as characterized by flow cytometry. Results are expressed as a dot plot from 1 representative experiment (top panel), and numbers represent the percentage of events in the corresponding quadrant. The cumulative results from 5 mice are shown (bottom panels). (C) C57BL/6 CD45.1⁺ mice were injected intravenously with 10⁵ DX5⁺ CD45.2⁺-enriched cells from IK^L/L Rag^−/− mice. The following day, mice were injected with PBS (top panel) or CpG-Dotap (bottom panel); and after 4 hours, IFN-γ production by injected (CD45.2⁺) or endogenous (CD45.2⁻) NK cells from the host spleen was determined by intracellular staining. The numbers in quadrants represent the percentage of cells in the selected gates. One representative experiment of 2 is shown.