B220⁺ NK cells acquire an mNK-cell phenotype on in vivo transfer. (A) Gating strategy used to sort B220⁺ NK cells from the spleen of B6.SJL (CD45.1) mice. Sorted cells are CD3⁻ CD19⁻ CD11c^low B220⁺ CD49b⁺. Cell purity was routinely > 90%. B220⁺ NK cells sorted from the spleen of B6.SJL (CD45.1) mice were adoptively transferred into (B) C57BL/6 (CD45.2) or (C) B6.Rag1^−/− (CD45.2) mice through tail vein injections. The spleen cells were analyzed 5 (B-C top) and 15 (B-C bottom) days after transfer. The expression of CD11b, CD27, CD49b, CD43, CD11c, and B220 on CD45.1⁺CD45.2⁻ transferred cells is shown. Results are representative of ≥ 3 independent experiments.