The presence of MHC-I ligand does not improve the responsiveness of Ly49A⁺ and Ly49G2⁺ CD8αα iIELs. (A) Representative histograms show H2-D^d staining of cells isolated from the small intestine (left) and spleen (right) from B6 D^d transgenic mice: grey line represents unstained control; and black line, H2-D^d stained. (B) MIP-1α production by CD8αα iIEL subpopulations from B6 (■) or B6 D^d () mice was determined after in vitro stimulation with plate-bound anti-CD3 mAb. Bar graph represents the mean (± SEM). MIP-1α production by the indicated iIEL subpopulations is shown relative to the iIEL subset lacking inhibitory MHC-I receptors for B6 D^d (n = 4) and B6 mice (n = 12). The data for B6 mice are the same as those shown in Figure 2A. *Significant difference (P < .05) in cytokine production by B6 D^d and B6 iIELs (Mann-Whitney). (C) MIP-1α and IFN-γ production by spleen NK cells from B6 (■) and B6 D^d () mice was determined after stimulation with plate-bound anti-NK1.1. NK cells (CD3⁻CD49b⁺) were further subdivided into Ly49A single-positive and Ly49C single-positive subsets. The mean (± SEM) cytokine production of Ly49A⁺ relative to Ly49C⁺ NK cells is shown (n = 3-5). *Significant difference (P < .05) between B6 and B6 D^d NK cells (Mann-Whitney).