Ly-49 antigen defines an αβ TCR population in i-IEL with an extrathymic maturation

NK cell self-tolerance is maintained by inhibitory receptors specific for MHC class I molecules. Inhibitory NK receptors are also expressed on memory CD8 T cells but their biological relevance on T cells is unclear. In this study, we describe the expression of the Ly49A receptor on a subset of autoreactive T cells which persist in mice double-transgenic for the lymphocytic choriomeningitis virus-derived peptide gp33 and a TCRαβ specific for the gp33. No Ly49A-expressing cells are found in TCRαβ single-transgenic mice, indicating that the presence of the autoantigen is required for Ly49A induction. Direct evidence for an Ag-specific initiation of Ly49A expression has been obtained in vitro after stimulation of autoreactive TCRαβ T cells with the cognate self-Ag. This expression of Ly49A substantially reduces Ag-specific activation of autoreactive T cells. These findings thus suggest that autoantigen-specific induction of inhibitory NK cell receptors on T cells may contribute to peripheral self-tolerance.

Section: Mabs and Gp33 Tetramersmentioning

confidence: 99%

Cutting Edge: Stimulation with the Cognate Self-Antigen Induces Expression of the Ly49A Receptor on Self-Reactive T Cells Which Modulates Their Responsiveness

Saurer

Seibold

Vallan

et al. 2003

“…One million nonadherent cells were incubated with 24G2 (anti-CD16/32) hybridoma supernatant to reduce background. Cells were stained with a mixture of NK1.1 PE and CD3 cychrome plus appropriate combinations of FITC-or biotin-labeled anti-Ly-49 mAbs: SW5E6 (Ly-49C/I); 4D11 (Ly-49G), 4E5 (Ly-49D) (all from PharMingen), JR9-318 (Ly-49A) (33), and 4LO3911 (Ly-49C) (34). EL-4 T cell lymphoma cells were stained with FITC-labeled Ly-49 mAbs (listed above) and propidium iodide to exclude dead cells.…”

Section: Flow Cytometrymentioning

confidence: 99%

Positive and Negative Roles of theTrans-Acting T Cell Factor-1 for the Acquisition of Distinct Ly-49 MHC Class I Receptors by NK Cells

Kunz

Held

2001

Members of the Ly-49 gene family code for class I MHC-specific receptors that regulate NK cell function. Due to a combinatorial distribution of Ly-49 receptors, NK cells display considerable clonal heterogeneity. The acquisition of one Ly-49 receptor, Ly-49A is strictly dependent on the transcriptional trans-acting factor T cell-specific factor-1 (TCF-1). Indeed, TCF-1 binds to two sites in the Ly-49a promoter and regulates its activity, suggesting that the Ly-49a gene is a direct TCF-1 target. TCF-1 deficiency resulted in the altered usage of additional Ly-49 receptors. We show in this study, using TCF-1 β2-microglobulin double-deficient mice, that these repertoire alterations are not due to Ly-49/MHC class I interactions. Our findings rather suggest a TCF-1-dependent, cell autonomous effect on the acquisition of multiple Ly-49 receptors. Besides reduced receptor usage (Ly-49A and D), we also observed no effect (Ly-49C) and significantly expanded (Ly-49G and I) receptor usage in the absence of TCF-1. These effects did not in all cases correlate with the presence of TCF binding sites in the respective proximal promoter. Therefore, besides TCF-1 binding to the proximal promoter, Ly-49 acquisition may also be regulated by TCF-1 binding to more distant cis-acting elements and/or by regulating the expression of additional trans-acting factors. Consistent with the observed differential, positive or negative role of TCF-1 for Ly-49 receptor acquisition, reporter gene assays revealed the presence of an inducing as well as a repressing TCF site in certain proximal Ly-49 promoters. These findings reveal an important role of TCF-1 for the formation of the NK cell receptor repertoire.

“…Anti-Ly49A (JR9-318 and A1), anti-Ly49C/I (SW5E6), and anti-Ly49G2 (4D11) have been described (21)(22)(23)(24). Abs against NK1.1 (PK136), CD3 (145-2C11), CD45.2 (104), and Thy-1 (30-H12) were purchased from PharMingen (San Diego, CA).…”

Section: Abs and Reagentsmentioning

confidence: 99%

Impaired Natural Killing of MHC Class I-Deficient Targets by NK Cells Expressing a Catalytically Inactive Form of SHP-1

Lowin-Kropf

Kunz

Beermann³

et al. 2000

NK cell function is negatively regulated by MHC class I-specific inhibitory receptors. Transduction of the inhibitory signal involves protein tyrosine phosphatases such as SHP-1 (SH2-containing protein tyrosine phosphatase-1). To investigate the role of SHP-1 for NK cell development and function, we generated mice expressing a catalytically inactive, dominant-negative mutant of SHP-1 (dnSHP-1). In this paper we show that expression of dnSHP-1 does not affect the generation of NK cells even though MHC receptor-mediated inhibition is partially impaired. Despite this defect, these NK cells do not kill syngeneic, normal target cells. In fact dnSHP-1-expressing NK cells are hyporesponsive toward MHC-deficient target cells, suggesting that non-MHC-specific NK cell activation is significantly reduced. In contrast, these NK cells mediate Ab-dependent cell-mediated cytotoxicity and prevent the engraftment with β2-microglobulin-deficient bone marrow cells. A similar NK cell phenotype is observed in viable motheaten (mev) mice, which show reduced SHP-1 activity due to a mutation in the Shp-1 gene. In addition, NK cells in both mouse strains show a tendency to express more inhibitory MHC-specific Ly49 receptors. Our results demonstrate the importance of SHP-1 for the generation of functional NK cells, which are able to react efficiently to the absence of MHC class I molecules from normal target cells. Therefore, SHP-1 may play an as-yet-unrecognized role in some NK cell activation pathways. Alternatively, a reduced capacity to transduce SHP-1-dependent inhibitory signals during NK cell development may be compensated by the down-modulation of NK cell triggering pathways.