B220⁺ NK cells are phenotypically similar but not identical to mNK cells. (A) The level of expression of various NK-cell markers from C57BL/6 mice gated on B220⁺, CD27⁺, and CD27⁻ NK-cell subsets is depicted. The mean fluorescence intensity is indicated. (B) Expression of CD11b and CD27 expression on B220⁺ NK cells and total CD49b⁺CD11c^low/−B220⁻ NK cells from both C57BL/6 and B6.Rag1^−/− mice are shown. (C) Expression of NK-cell maturation markers, namely CD43 and Ly108, on B220⁺, CD27⁺, and CD27⁻ NK-cell subsets from C57BL/6 and B6.Rag1^−/− mice is shown. Results are representative of ≥ 3 independent experiments.