Most proteins encoded by members of the Ly-49 gene family are class I- recognizing receptors on murine natural killer (NK) cells. Class I recognition by Ly-49 receptors usually results in inhibition of NK cell lysis of target cells. However, NK cells function not only in a lytic capacity, but also can mediate cytokine production. We have demonstrated the ability of Ly-49A and Ly-49G2 to regulate production of cytokines by NK cells as a result of target MHC. The production of IFN-gamma and GM-CSF by NK cells were regulated by target cells expressing the appropriate class I molecules. Ly-49A and G2 were found to inhibit cytokine induction by NK cells. Examination of mRNA for IFN-gamma and GM-CSF indicated that Ly-49 receptors induced transcriptional regulation of NK cells. These results demonstrate that class I binding of these NK receptors can inhibit production of important physiological cytokines, in addition to the regulation of cytotoxic activity. Although infrequent on T cells, some CD3+ cells express Ly-49's. The non-MHC restricted lysis and cytokine production [IFN and GM-CSF] of CD3+, IL-2 cultured T cells were modulated by antibodies to either Ly-49A & G2 or to class I [H-2Ddalpha1/alpha2]. These results indicate that Ly-49 class I binding receptors, previously thought restricted to NK cells, can regulate important physiological functions of T cell subsets. Murine NK cells express both inhibitory (Ly-49A, C, & G2) and activating receptors (Ly-49D). This dichotomy of function between Ly-49 family members suggested different signaling events upon receptor/ligand interaction. We have demonstrated that: 1) in transfected Cos7 and murine NK cells Ly-49A, C, and G2 are phosphorylated following pervanadate stimulation, whereas Ly-49D is not; 2) monoclonal antibody-induced receptor ligation mediates tyrosine phosphorylation of Ly-49A and G2, but not Ly-49D; 3) SHP-1 coprecipitates with Ly-49A and G2 following receptor phosphorylation; and 4) tyrosine phosphorylation of Ly-49 inhibitory receptors may depend on tyrosine residues restricted to the ITIM (immunoreceptor tyrosine-based inhibitory motif). Our data further supports the involvement of ITIMs as crucial sequences regulating receptor-mediated inhibitory functions in NK cells.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Intramural Research (Z01)
Project #
1Z01BC009247-18
Application #
6100947
Study Section
Special Emphasis Panel (LEI)
Project Start
Project End
Budget Start
Budget End
Support Year
18
Fiscal Year
1998
Total Cost
Indirect Cost
Name
National Cancer Institute Division of Basic Sciences
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Ortaldo, John R; Winkler-Pickett, Robin T; Bere Jr, Earl W et al. (2005) In vivo hydrodynamic delivery of cDNA encoding IL-2: rapid, sustained redistribution, activation of mouse NK cells, and therapeutic potential in the absence of NKT cells. J Immunol 175:693-9
Ortaldo, John R; Young, Howard A (2005) Mouse Ly49 NK receptors: balancing activation and inhibition. Mol Immunol 42:445-50
Ortaldo, John R; Young, Howard A; Winkler-Pickett, Robin T et al. (2004) Dissociation of NKT stimulation, cytokine induction, and NK activation in vivo by the use of distinct TCR-binding ceramides. J Immunol 172:943-53
Mason, Llewellyn H; Willette-Brown, Jami; Anderson, Stephen K et al. (2003) Receptor glycosylation regulates Ly-49 binding to MHC class I. J Immunol 171:4235-42
Ortaldo, John R; Young, Howard A (2003) Expression of IFN-gamma upon triggering of activating Ly49D NK receptors in vitro and in vivo: costimulation with IL-12 or IL-18 overrides inhibitory receptors. J Immunol 170:1763-9
Raziuddin, A; Bennett, M; Winkler-Pickett, R et al. (2000) Synergistic effects of in vivo depletion of Ly-49A and Ly-49G2 natural killer cell subsets in the rejection of H2(b) bone marrow cell allografts. Blood 95:3840-4
Peacock, C D; Lin, M Y; Ortaldo, J R et al. (2000) The virus-specific and allospecific cytotoxic T-lymphocyte response to lymphocytic choriomeningitis virus is modified in a subpopulation of CD8(+) T cells coexpressing the inhibitory major histocompatibility complex class I receptor Ly49G2. J Virol 74:7032-8
Mason, L H; Willette-Brown, J; Mason, A T et al. (2000) Interaction of Ly-49D+ NK cells with H-2Dd target cells leads to Dap-12 phosphorylation and IFN-gamma secretion. J Immunol 164:603-11
Bosco, M C; Curiel, R E; Zea, A H et al. (2000) IL-2 signaling in human monocytes involves the phosphorylation and activation of p59hck. J Immunol 164:4575-85
Ortaldo, J R; Winkler-Pickett, R; Wiegand, G (2000) Activating Ly-49D NK receptors: expression and function in relation to ontogeny and Ly-49 inhibitor receptors. J Leukoc Biol 68:748-56

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