A subset of NK cells lacking known inhibitory receptors specific for self-MHC molecules. Freshly isolated B6 splenocytes were depleted of T cells, including NK1.1⁺ T cells, and stained with mAbs specific for NK1.1, Ly49C, Ly49I, and NKG2. Control staining was performed with control rat IgG (Ig ctrl.) instead of anti-NKG2 mAb and streptavidin-PE alone instead of anti-Ly49C and anti-Ly49I mAbs (ctrl.). Dot plots are gated on NK1.1⁺ cells. Numbers in the quadrants represent mean percentages ± SEM (n = 3 mice). An average of 11.4% of the NK cells lacked Ly49C, Ly49I, and CD94/NKG2 (CI/NKG2^- NK cells).