Ly49A- and Ly49G2-expressing CD8αα iIELs are hyporesponsive. MIP-1α and lymphotactin production by B6 iIELs on stimulation with plate-bound anti-CD3 mAb (A-B) or on stimulation with PMA/ionomycin (C-D) as determined by intracellular staining of CD8αα iIELs (co-)expressing Ly49A, Ly49G2, and/or NKG2A/C/E. MIP-1α and lymphotactin production, corrected for background staining (no anti-CD3 mAb), is shown as the percentage of positive cells within each CD8αα cell subpopulation (mean ± SEM; n = 12). *Significant difference (P < .05) compared with CD8αα iIELs lacking inhibitory MHC-I receptors (Mann-Whitney). (E) Histograms represent CD69 expression on B6 iIELs on stimulation with plate-bound anti-CD3 mAb: grey line represents unstained control; dashed line, no stimulation; and black line, anti-CD3 stimulation. Numbers indicate the mean percentage (± SEM) of CD69^high cells in the indicated iIEL subpopulation on TCR-triggering (n = 5). *Significant (P < .05) CD69 up-regulation compared with CD8αα iIELs lacking inhibitory MHC-I receptors (Mann-Whitney).