title: The Ly-49D receptor activates murine natural killer cells.
abstract: Proteins encoded by members of the Ly-49 gene family are predominantly expressed on murine natural killer (NK) cells. Several members of this gene family have been demonstrated to inhibit NK cell lysis upon recognizing their class I ligands on target cells. In this report, we present data supporting that not all Ly-49 proteins inhibit NK cell function. Our laboratory has generated and characterized a monoclonal antibody (mAb) (12A8) that can be used to recognize the Ly-49D subset of murine NK cells. Transfection of Cos-7 cells with known members of the Ly-49 gene family revealed that 12A8 recognizes Ly-49D, but also cross-reacts with the Ly-49A protein on B6 NK cells. In addition, 12A8 demonstrates reactivity by both immuno-precipitation and two-color flow cytometry analysis with an NK cell subset that is distinct from those expressing Ly-49A, C, or G2. An Ly-49D+ subset of NK cells that did not express Ly-49A, C, and G2 was isolated and examined for their functional capabilities. Tumor targets and concanovalin A (ConA) lymphoblasts from a variety of H2 haplotypes were examined for their susceptibility to lysis by Ly-49D+ NK cells. None of the major histocompatibility complex class I-bearing targets inhibited lysis of Ly-49D+ NK cells. More importantly, we demonstrate that the addition of mAb 12A8 to Ly-49D+ NK cells can augment lysis of Fc gamma R+ target cells in a reverse antibody-dependent cellular cytotoxicity-type assay and induces apoptosis in Ly-49D+ NK cells. Furthermore, the cytoplasmic domain of Ly-49D does not contain the V/Ix-YxxL immunoreceptor tyrosine-based inhibitory motif found in Ly-49A, C, or G2 that has been characterized in the human p58 killer inhibitory receptors. Therefore, Ly-49D is the first member of the Ly-49 family characterized as transmitting positive signals to NK cells, rather than inhibiting NK cell function.
authors.affiliation: Laboratory of Experimental Immunology, SAIC Frederick, National Cancer Institute-FCRDC, Maryland 21702-1201, USA.
authors.forename: L H
authors.initials: LH
authors.lastname: Mason
authors.forename: S K
authors.initials: SK
authors.lastname: Anderson
authors.forename: W M
authors.initials: WM
authors.lastname: Yokoyama
authors.forename: H R
authors.initials: HR
authors.lastname: Smith
authors.forename: R
authors.initials: R
authors.lastname: Winkler-Pickett
authors.forename: J R
authors.initials: JR
authors.lastname: Ortaldo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D017209:Apoptosis; D019556:COS Cells; D016384:Consensus Sequence; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D037181:Lectins, C-Type; D008213:Lymphocyte Activation; D051379:Mice; D008969:Molecular Sequence Data; D005810:Multigene Family; D051381:Rats; D011971:Receptors, Immunologic / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D055630:Receptors, NK Cell Lectin-Like; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000276:immunology; D017386:Sequence Homology, Amino Acid; D013154:Spleen / Q000201:enzymology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D000950:Antigens, Ly; D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D011971:Receptors, Immunologic; D055630:Receptors, NK Cell Lectin-Like; D011994:Recombinant Proteins