NKG2D-ligand expression levels on ConA-induced lymphoblasts correlates with the magnitude of NKG2D-dependent activation of F1 NK cells. (A) Lymphoblasts from BALB/c and C.B10 were stained for the indicated NKG2D ligands. (B) CB6F1 NK cells incubated with lymphoblasts of the indicated strains with or without a neutralizing anti-NKG2D mAb in the presence of anti-CD107a to detect degranulation. % specific degranulation (CD107a) of the total F1 NK-cell population is shown. *P = .04, **P = .002. (C) Specific degranulation of F1 NK cells within the subsets defined by single expression of Ly49C/I, Ly49A, and Ly49G2 in response to stimulation with the indicated lymphoblasts in the presence of control IgG or a neutralizing anti-NKG2D mAb. *P < .01 Ly49C/I versus either Ly49A or Ly49G2 group; **P < .007 versus Ly49G2 versus Ly49C/I group. Data are representative of 3 independent experiments. NS indicates not significant over background.