Ly-49C(B6) NK inhibitory receptor recognizes peptide-receptive H-2K(b)

NK-mediated cytotoxicity involves two families of receptors: activating rec eptors that trigger lysis of the target cells being recognized and inhibito ry receptors specific primarily for MHC I on the target cell surface that c an override the activating signal. MHC I molecules on the cell surface can be classified into molecules made stable by the binding of peptide with hig h affinity or unstable molecules potentially capable of binding high affini ty peptide (hence, peptide receptive) and being converted into stable molec ules. It has been previously shown that the Ly-49A inhibitory receptor reco gnizes stable Dd molecules. We show in this study that the inhibitory recep tor Ly-49C(B6) recognizes peptide-receptive Kb molecules, but does not reco gnize K-b molecules once they have bound high affinity peptide.