Cell-surface phenotype of CI/NKG2⁺ and CI/NKG2^- NK subsets. Freshly isolated splenocytes from B6 mice (A) or β2m^-/- mice (B) were stained with mAbs for the 3 self-specific receptors (Ly49C, Ly49I, and NKG2), NK1.1, CD3, and the other markers indicated. Expression of various markers was compared on gated CI/NKG2⁺NK1.1⁺CD3^- cells (solid line) and CI/NKG2^-NK1.1⁺CD3^- cells (dashed line), except the NK1.1 staining, which was gated on CD3^-NKG2D⁺ cells. The first histogram represents the negative control for all the samples with the exception of NKG2D; the negative control for NKG2D staining is the shaded histogram within that panel.