scholarly journals A subset of natural killer cells achieves self-tolerance without expressing inhibitory receptors specific for self-MHC molecules

Blood ◽  
2005 ◽  
Vol 105 (11) ◽  
pp. 4416-4423 ◽  
Author(s):  
Nadine C. Fernandez ◽  
Emmanuel Treiner ◽  
Russell E. Vance ◽  
Amanda M. Jamieson ◽  
Suzanne Lemieux ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Class I ◽  
Inhibitory Receptor ◽  
Inhibitory Receptors ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecule ◽  
Self Tolerance

Abstract It is widely believed that self-tolerance of natural killer (NK) cells occurs because each NK cell expresses at least one inhibitory receptor specific for a host major histocompatibility complex (MHC) class I molecule. Here we report that some NK cells lack all known self-MHC–specific inhibitory receptors, yet are nevertheless self-tolerant. These NK cells exhibit a normal cell surface phenotype and some functional activity. However, they respond poorly to class I–deficient normal cells, tumor cells, or cross-linking of stimulatory receptors, suggesting that self-tolerance is established by dampening stimulatory signaling. Thus, self-tolerance of NK cells in normal animals can occur independently of MHC-mediated inhibition, and hyporesponsiveness plays a role in self-tolerance of NK cells, as also proposed for B and T cells.

scholarly journals Acquisition of Ly49 Receptor Expression by Developing Natural Killer Cells

1998 ◽  
Vol 187 (4) ◽  
pp. 609-618 ◽  
Author(s):  
Jeffrey R. Dorfman ◽  
David H. Raulet
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Receptor Expression ◽  
Class I ◽  
Cell Repertoire ◽  
Class I Mhc ◽  
Mhc Molecules ◽  
Histocompatibility Complex

The formation of the repertoire of mouse natural killer (NK) cell receptors for major histocompatibility complex (MHC) class I molecules was investigated by determining the developmental pattern of Ly49 receptor expression. During the first days after birth, few or no splenic NK cells express Ly49A, Ly49C, Ly49G2, or Ly49I receptors. The proportion of Ly49+ splenic NK cells gradually rises to adult levels during the first 6–8 wk of life. The appearance of appreciable numbers of splenic Ly49+ NK cells coincides with the appearance of NK activity at 3–4 wk. After in vivo transfer, NK cells not expressing specific Ly49 receptors can give rise to NK cells that do, and cells expressing one of these four Ly49 receptors can give rise to cells expressing others. Once initiated, expression of a Ly49 receptor is stable for at least 10 d after in vivo transfer. Hence, initiation of Ly49 receptor expression occurs successively. Interestingly, expression of one of the receptors tested, Ly49A, did not occur after in vivo transfer of Ly49A− cells. One possible explanation for these data is that the order of Ly49 receptor expression by NK cells is nonrandom. The results provide a framework for evaluating models of NK cell repertoire formation, and how the repertoire is molded by host class I MHC molecules.

scholarly journals Nonstochastic Coexpression of Activation Receptors on Murine Natural Killer Cells

2000 ◽  
Vol 191 (8) ◽  
pp. 1341-1354 ◽  
Author(s):  
Hamish R.C. Smith ◽  
Hubert H. Chuang ◽  
Lawrence L. Wang ◽  
Margarita Salcedo ◽  
Jonathan W. Heusel ◽  
...  
Keyword(s):  
Natural Killer Cells ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Inhibitory Receptors ◽  
Antigen Receptors ◽  
Killer Cells ◽  
Histocompatibility Complex ◽  
Nk Cell Cytotoxicity

Murine natural killer cells (NK) express lectin-like activation and inhibitory receptors, including the CD94/NKG2 family of receptors that bind Qa-1, and the Ly-49 family that recognizes major histocompatibility complex class I molecules. Here, we demonstrate that cross-linking of NK cells with a new specific anti–Ly-49H mAb induced NK cell cytotoxicity and cytokine production. Ly-49H is expressed on a subset of NK cells and can be coexpressed with Ly-49 inhibitory receptors. However, unlike Ly-49 inhibitory receptors, Ly-49H is not detectable on naive splenic CD3+ T cells, indicating that Ly-49H may be an NK cell–specific activation receptor. In further contrast to the stochastically expressed Ly-49 inhibitory receptors, Ly-49H is preferentially expressed with the Ly-49D activation receptor, and expression of both Ly-49H and Ly-49D is augmented on NK cells that lack receptors for Qa-1 tetramers. On developing splenic NK1.1+ cells, Ly-49D and Ly-49H are expressed later than the inhibitory receptors. These results directly demonstrate that Ly-49H activates primary NK cells, and suggest that expression of Ly-49 activation receptors by NK cells may be specifically regulated on NK cell subsets. The simultaneous expression of multiple activation receptors by individual NK cells contrasts with that of T cell antigen receptors and is relevant to the role of NK cells in innate immunity.

Human Natural Killer Cells Achieve Tolerance by Preferentially Endowing Functional Competence to Inhibitory Killer Ig-Like Receptors Specific for Self-HLA Class I.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 919-919
Author(s):  
Junli Yu ◽  
Clara Pinto-Agnello ◽  
Joseph Chewning ◽  
Katharine C. Hsu
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Class I ◽  
Target Cells ◽  
Inhibitory Receptors ◽  
Hla Ligand ◽  
Self Tolerance ◽  
Hla Ligands ◽  
Ifn Γ ◽  
Haplotype A

Abstract Natural killer (NK) cells are capable of cytotoxic targeting of virally infected cells and some tumor cells. It has been well-demonstrated that NK cells recognize target cells that have down-regulated MHC class I antigen expression (i.e. “missing self recognition”), and that it is the lack of class I engagement of inhibitory receptors such as the killer Ig-like receptors (KIR) that thereby allows NK activation and effector function. How these same inhibitory receptors achieve self-tolerance and simultaneously avoid autoimmunity in humans has not been clear, as more than 60% of individuals have inhibitory KIR for which they lack the HLA ligand. We demonstrate that mature NK cells achieve self-tolerance by preferentially endowing functional competence to the inhibitory KIRs for which they exhibit the cognate HLA ligands. To allow evaluation of inhibitory KIR and avoid interference from potentially class-I recognizing activating KIR, we analyzed NK cells from 10 individuals with various HLA backgrounds, but who were all homozygous for KIR haplotype-A. KIR haplotype-A contains the inhibitory KIR receptors 2DL3, 2DL1, and 3DL1, specific for HLA-Cw3, -Cw4, and -Bw4 ligands respectively, in addition to at most one other activating KIR whose ligand is unknown. Using 6-color staining and flow cytometric analysis of intracellular IFN-γ production, we evaluated the responsiveness of 30 inhibitory KIR-expressing NK subsets following activation with 721.221, a target cell line deficient in class I expression, with 721.221 transfectants expressing HLA-Cw3, -Cw4, or -Bw4 ligands, and with B-lymphocyte cell lines with diverse HLA phenotypes. NK cells exclusively expressing an inhibitory KIR for self-HLA demonstrated increased IFN-γ when coincubated with target cells lacking the cognate HLA ligand, whereas NK cells exclusively expressing an inhibitory KIR for non-self HLA were hyporesponsive to all targets. In all individuals, NK cells expressing inhibitory KIR specific for self-HLA were significantly more responsive than NK cells expressing inhibitory KIR for non-self HLA (p<0.001). All 3 inhibitory KIR (KIR2DL3, 2DL1, and 3DL1) demonstrated capacity for tolerance, with predictable response patterns based on the HLA background of the individual. NK cells lacking all inhibitory NK receptors (KIR−CD94/NKG2A−ILT2−) were identifiable and were markedly hyporesponsive. KIR−CD94/NKG2A+ILT2+ NK cells were also minimally responsive, comparable to the NK subset expressing inhibitory KIR for non-self HLA. These results demonstrate NK tolerance in humans, consistent with the licensing model proposed in mice: NK cells expressing inhibitory KIR to self-HLA are significantly more responsive than NK cells expressing inhibitory KIR for non-self HLA, and are rendered tolerant to self through inhibition upon binding to self-HLA ligands. NK cells expressing inhibitory KIR for non-self HLA are hyporesponsive and therefore rendered tolerant and incapable of autoreactivity when ligand is not engaged.

Analysis of natural killer cells in TAP2-deficient patients: expression of functional triggering receptors and evidence for the existence of inhibitory receptor(s) that prevent lysis of normal autologous cells

Blood ◽  
2002 ◽  
Vol 99 (5) ◽  
pp. 1723-1729 ◽  
Author(s):  
Massimo Vitale ◽  
Jacques Zimmer ◽  
Roberta Castriconi ◽  
Daniel Hanau ◽  
Lionel Donato ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Antigen Processing ◽  
Nk Cell ◽  
Hla Class I ◽  
Surface Expression ◽  
Class I ◽  
Inhibitory Receptor ◽  
Surface Receptors ◽  
Hla Class I Molecules

Natural killer (NK) cells are characterized by the ability to kill cells that lack HLA class I molecules while sparing autologous normal (HLA class I+) cells. However, patients with transporter-associated antigen processing (TAP) deficiency, though displaying strong reductions of HLA class I surface expression, in most instances do not experience NK-mediated autoimmune phenomena. A possible mechanism by which TAP−/− NK cells avoid autoreactivity against autologous HLA class I–deficient cells could be based on either quantitative or qualitative defects of surface receptors involved in NK cell triggering. In this study we show that NK cells derived from 2 patients with TAP2−/− express normal levels of all known triggering receptors. As revealed by the analysis of polyclonal and clonal NK cells, these receptors display normal functional capabilities and allow the killing of a panel of NK-susceptible targets, including autologous B-LCLs. On the other hand, TAP2−/− NK cells were unable to kill either allogeneic (HLA class I+) or autologous (HLA class I− ) phytohemagglutinin (PHA) blasts even in the presence of anti-HLA class I monoclonal antibody. These data suggest that TAP2−/− NK cells express still unknown inhibitory receptor(s) capable of down-regulating the NK cell cytotoxicity on binding to surface ligand(s) expressed by T cell blasts. Functional analyses, both at the polyclonal and at the clonal level, are consistent with the concept that the putative inhibitory receptor is expressed by virtually all TAP2−/− NK cells, whereas it is present only in rare NK cells from healthy persons. Another possibility would be that TAP2−/− NK cells are missing a still unidentified triggering receptor involved in NK cell-mediated killing of PHA blasts.

scholarly journals Transgenic expression of the Ly49A natural killer cell receptor confers class I major histocompatibility complex (MHC)-specific inhibition and prevents bone marrow allograft rejection.

1996 ◽  
Vol 184 (5) ◽  
pp. 2037-2041 ◽  
Author(s):  
W Held ◽  
D Cado ◽  
D H Raulet
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Major Histocompatibility Complex ◽  
Nk Cells ◽  
Natural Killer ◽  
Nk Cell ◽  
Class I ◽  
Specific Inhibition ◽  
Transgenic Expression ◽  
Histocompatibility Complex

Natural killer (NK) cells and some T cells are endowed with receptors specific for class I major histocompatibility complex (MHC) molecules that can inhibit cellular effector functions. The function of the Ly49 receptor family has been studied in vitro, but no gene transfer experiments have directly established the role of these receptors in NK cell functions. We show here that transgenic expression of the H-2Dd-specific Ly49A receptor in all NK cells and T cells conferred class I-specific inhibition of NK cell-mediated target cell lysis as well as of T cell proliferation. Furthermore, transgene expression prevented NK cell-mediated rejection of allogeneic H-2d bone marrow grafts by irradiated mice. These results demonstrate the function and specificity of Ly49 receptors in vivo, and establish that their subset-specific expression is necessary for the discrimination of MHC-different cells by NK cells in unmanipulated mice.

scholarly journals Inhibitory Receptors Alter Natural Killer Cell Interactions with Target Cells Yet Allow Simultaneous Killing of Susceptible Targets

1999 ◽  
Vol 190 (7) ◽  
pp. 1005-1012 ◽  
Author(s):  
Mikael Eriksson ◽  
Guenther Leitz ◽  
Erik Fällman ◽  
Ove Axner ◽  
James C. Ryan ◽  
...  
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Mhc Class I ◽  
Optical Tweezers ◽  
Target Cell ◽  
Nk Cell ◽  
Killer Cell ◽  
Class I ◽  
Target Cells ◽  
Inhibitory Receptors

Inhibitory receptors expressed on natural killer (NK) cells abrogate positive signals upon binding corresponding major histocompatibility complex (MHC) class I molecules on various target cells. By directly micromanipulating the effector–target cell encounter using an optical tweezers system which allowed temporal and spatial control, we demonstrate that Ly49–MHC class I interactions prevent characteristic cellular responses in NK cells upon binding to target cells. Furthermore, using this system, we directly demonstrate that an NK cell already bound to a resistant target cell may simultaneously bind and kill a susceptible target cell. Thus, although Ly49-mediated inhibitory signals can prevent many types of effector responses, they do not globally inhibit cellular function, but rather the inhibitory signal is spatially restricted towards resistant targets.

scholarly journals Genetic Variability of the Major Histocompatibility Complex Class I Homologue Encoded by Human Cytomegalovirus Leads to Differential Binding to the Inhibitory Receptor ILT2

2005 ◽  
Vol 79 (4) ◽  
pp. 2251-2260 ◽  
Author(s):  
Mar Valés-Gómez ◽  
Mitsunori Shiroishi ◽  
Katsumi Maenaka ◽  
Hugh T. Reyburn
Keyword(s):  
Major Histocompatibility Complex ◽  
Nk Cells ◽  
Mhc Class I ◽  
Human Cytomegalovirus ◽  
Class I ◽  
Inhibitory Receptor ◽  
Major Histocompatibility ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
Virus Isolates

ABSTRACT Human cytomegalovirus carries a gene, UL18, that is homologous to cellular major histocompatibility complex (MHC) class I genes. Like MHC class I molecules, the protein product of the UL18 gene associates with β2-microglobulin, and the stability of this complex depends on peptide loading. UL18 protein binds to ILT2 (CD85j), an inhibitory receptor present on B cells, monocytes, dendritic cells, T cells, and NK cells that also recognizes classical and nonclassical MHC molecules. These observations suggest that UL18 may play a role in viral immune evasion, but its real function is unclear. Since this molecule has similarity with polymorphic MHC proteins, we explored whether the UL18 gene varied between virus isolates. We report here that the UL18 gene varies significantly between virus isolates: amino acid substitutions were found in the predicted α1, α2, and α3 domains of the UL18 protein molecule. We also studied the ability of several variant UL18 proteins to bind to the ILT2 receptor. All of the variants tested bound to ILT2, but there were marked differences in the affinity of binding to this receptor. These differences were reflected in functional assays measuring inhibition of the cytotoxic capacity of NK cells via interaction with ILT2. In addition, the variants did not bind other members of the CD85 family. The implications of these data are discussed.

scholarly journals Natural Killer Cell Tolerance in Mice with Mosaic Expression of Major Histocompatibility Complex Class I Transgene

1997 ◽  
Vol 186 (3) ◽  
pp. 353-364 ◽  
Author(s):  
Maria H. Johansson ◽  
Charles Bieberich ◽  
Gilbert Jay ◽  
Klas Kärre ◽  
Petter Höglund
Keyword(s):  
Major Histocompatibility Complex ◽  
Nk Cells ◽  
Natural Killer ◽  
Mhc Class I ◽  
Nk Cell ◽  
Class I ◽  
Cell Tolerance ◽  
Histocompatibility Complex ◽  
Missing Self

We have studied natural killer (NK) cell tolerance in a major histocompatibility complex (MHC) class I transgenic line, DL6, in which the transgene product was expressed on only a fraction of blood cells. In contrast with transgenic mice expressing the same transgene in all cells, NK cells from mosaic mice failed to reject transgene-negative bone marrow or lymphoma grafts. However, they retained the capability to reject cells with a total missing-self phenotype, i.e., cells lacking also wild-type MHC class I molecules. Tolerance against transgene-negative cells was demonstrated also in vitro, and could be broken if transgene-positive spleen cells of mosaic mice were separated from negative cells before, or after 4 d of culture in interleukin-2. The results provide support for selective NK cell tolerance to one particular missing-self phenotype but not to another. We suggest that this tolerance is determined by NK cell interactions with multiple cells in the environment, and that it is dominantly controlled by the presence of cells lacking a specific MHC class I ligand. Furthermore, the tolerant NK cells could be reactivated in vitro, which suggests that the tolerance occurs without deletion of the potentially autoreactive NK cell subset(s), and that it may be dependent upon the continuous presence of tolerizing cells.

scholarly journals Models for Natural Killer Cell Repertoire Formation

2003 ◽  
Vol 10 (2-4) ◽  
pp. 183-192 ◽  
Author(s):  
Mali Salmon-Divon ◽  
Petter Höglund ◽  
Ramit Mehr
Keyword(s):  
Nk Cells ◽  
Natural Killer ◽  
Mhc Class I ◽  
Killer Cell ◽  
Stable Expression ◽  
Class I ◽  
Inhibitory Receptors ◽  
Cell Repertoire ◽  
Class I Mhc ◽  
Mhc Molecules

Natural killer (NK) cells lyse only cells that do not express sufficient levels of self class I MHC molecules. Inhibition of lysis is mediated by inhibitory receptors expressed by NK cells, such as the murine Ly49 receptors, that bind to MHC class I molecules. Since inhibitory receptor genes and MHC class I genes are located on different chromosomes, and are hence not automatically co-inherited, NK cells apparently adapt to the MHC environment during their development. Two models have been proposed to account for this “education” process of NK cells. Thetwo-step selectionmodel postulates that developing NK cells initiate the stable expression of a random set of Ly49 genes, and then undergo two selection steps, one for cells that express a sufficient number of self-MHC receptors, and one against cells that express too many inhibitory receptors. Thesequentialmodel postulates that a cell keeps initiating the stable expression of additional inhibitory receptors until a sufficient expression level of self-MHC specific receptors is reached, and the cell matures. In this study we implement both models in computer simulations, and compare simulation results to experimental data, in order to evaluate the relative plausibility of the two models.

scholarly journals Mouse CD94/NKG2A Is a Natural Killer Cell Receptor for the Nonclassical Major Histocompatibility Complex (MHC) Class I Molecule Qa-1b

1998 ◽  
Vol 188 (10) ◽  
pp. 1841-1848 ◽  
Author(s):  
Russell E. Vance ◽  
Jennifer R. Kraft ◽  
John D. Altman ◽  
Peter E. Jensen ◽  
David H. Raulet
Keyword(s):  
Major Histocompatibility Complex ◽  
Nk Cells ◽  
Natural Killer ◽  
Mhc Class I ◽  
Killer Cell ◽  
Class I ◽  
Target Cells ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Mhc Class I Molecule

Natural killer (NK) cells preferentially lyse targets that express reduced levels of major histocompatibility complex (MHC) class I proteins. To date, the only known mouse NK receptors for MHC class I belong to the Ly49 family of C-type lectin homodimers. Here, we report the cloning of mouse NKG2A, and demonstrate it forms an additional and distinct class I receptor, a CD94/NKG2A heterodimer. Using soluble tetramers of the nonclassical class I molecule Qa-1b, we provide direct evidence that CD94/NKG2A recognizes Qa-1b. We further demonstrate that NK recognition of Qa-1b results in the inhibition of target cell lysis. Inhibition appears to depend on the presence of Qdm, a Qa-1b-binding peptide derived from the signal sequences of some classical class I molecules. Mouse NKG2A maps adjacent to CD94 in the heart of the NK complex on mouse chromosome six, one of a small cluster of NKG2-like genes. Our findings suggest that mouse NK cells, like their human counterparts, use multiple mechanisms to survey class I expression on target cells.

Sign in / Sign up

Export Citation Format

Share Document