Specific combinations of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (... more Specific combinations of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (HLA) class I molecules characterized by a particular residue 80 are significantly associated with outcomes in different pathologic conditions, such as autoimmunity, pathogenic infection, cancer, and reproductive failure. Thus, a simplified method for HLA typing used in association with the analysis of KIR genotype (Kirotype) is of particular interest to extend the analysis of larger series. Here, we describe a quick and inexpensive method that allows use of pyrosequencing, a helpful subtyping of HLA class I molecules, into HLA-Bw6,-Bw4 I 80 or-Bw4 T 80 , HLA-C1, or-C2 groups and HLA-A allotypes sharing Bw4ϩ epitope or the rare HLA-B allotypes displaying the C1 motif. In particular, this analysis is focused on the amino acids around residue 80, known to be relevant in defining the affinity of KIR/HLA interaction and in the functional effects. This method was demonstrated to have good sensitivity, specificity, and reproducibility of detection and it was validated using a panel of HLA-typed International Histocompatibility Workshop (IHW) cell lines and clinical isolates. Using an allele quantitative acquisition mode, the method permitted us to obtain an accurate sequencing as required in heterozygous and/or homozygous sample definition.
International Archives of Allergy and Immunology, 1992
Drug Dosage The authors and the publisher have exerted every effort to ensure that drug selection... more Drug Dosage The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text arc in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the con stant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly impor tant when the recommended agent is a new and/or infre quently employed drug. All rights reserved. No part of this publication may be translated into other lan guages. reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying record ing. microcopying, or by any information storage and re trieval system, without permission in writing from the pub lisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center (see 'Infor mation for Readers and Subscribers').
2B4 is a surface molecule involved in activation of the natural killer (NK) cell–mediated cytotox... more 2B4 is a surface molecule involved in activation of the natural killer (NK) cell–mediated cytotoxicity. It binds a protein termed Src homology 2 domain–containing protein (SH2D1A) or signaling lymphocyte activation molecule (SLAM)-associated protein (SAP), which in turn has been proposed to function as a regulator of the 2B4-associated signal transduction pathway. In this study, we analyzed patients with X-linked lymphoproliferative disease (XLP), a severe inherited immunodeficiency characterized by critical mutations in the SH2D1A gene and by the inability to control Epstein-Barr virus (EBV) infections. We show that, in these patients, 2B4 not only fails to transduce triggering signals, but also mediates a sharp inhibition of the NK-mediated cytolysis. Other receptors involved in NK cell triggering, including CD16, NKp46, NKp44, and NKp30, displayed a normal functional capability. However, their activating function was inhibited upon engagement of 2B4 molecules. CD48, the natural l...
Proceedings of the National Academy of Sciences, 1999
Trophoblastic cells lack classical HLA class I and class II molecules but express HLA-G1. Althoug... more Trophoblastic cells lack classical HLA class I and class II molecules but express HLA-G1. Although this may prevent allorecognition by maternal T cells, it renders trophoblastic cells potentially susceptible to lysis by natural killer (NK) cells. As shown here, only a fraction of peripheral-blood NK cells in pregnant women express the HLA-G1-specific CD94/NKG2A and/or LIR-1 receptors. However, all NK cells isolated from maternal decidua during the first trimester expressed either one or both of these receptors. Perhaps more importantly, a fraction of cells expressed p49, an HLA-G1-specific inhibitory receptor, undetectable in peripheral-blood NK cells. p49 was expressed on virtually all NK cells isolated from placenta at term. Functional analyses revealed that the HLA class I-negative 221 lymphoblastoid cell line transfected with HLA-G1 was only partially protected from lysis by peripheral-blood NK cells isolated from pregnant women, whereas it was fully protected from decidual NK c...
Proceedings of the National Academy of Sciences of the United States of America, Jan 20, 2002
Previous studies showed that a subset of CD8(+) cytolytic T lymphocytes expressing HLA class I-sp... more Previous studies showed that a subset of CD8(+) cytolytic T lymphocytes expressing HLA class I-specific natural killer inhibitory receptors (iNKR) is characterized by the ability to recognize HLA-E and to mediate T cell receptor-dependent killing of different NK cell-susceptible tumor target cells. In this study, we show that this CD8(+) T cell subset can also undergo extensive proliferation in mixed lymphocyte cultures in response to allogeneic cells. Analysis of their cytolytic activity revealed a broad specificity against a panel of allogeneic phytohemagglutinin-induced blasts derived from HLA-unmatched donors. On the other hand, autologous and certain allogeneic phytohemagglutinin blasts were resistant to lysis. We used as target cells the transporter associated with antigen processing (TAP)-2(-/-) murine RMA-S cell line cotransfected with beta2-microglobulin and HLA-E*01033. On loading these cells with different HLA-E-binding peptides derived either from HLA class I leader sequ...
... We wish to thank Mrs. Cinzia Miriello and Mr. Stefano Canu for their skillful assistance in t... more ... We wish to thank Mrs. Cinzia Miriello and Mr. Stefano Canu for their skillful assistance in the preparation of the manuscript. ... 16. Moretta A, Bottino C, Pende D, Tripodi G, Tambussi G, Viale 0, Orengo AM, Barbaresi M, Merli A, Ciccone E, Moretta L. Identification of four subsets of ...
Large numbers of natural killer cells are present within the maternal decidua close to the extrav... more Large numbers of natural killer cells are present within the maternal decidua close to the extravillous trophoblast cells. Most of these natural killer cells express high levels of () inhibitory NK receptors KIR specific for HLA class I molecules. Since trophoblast cells only express HLA-C and HLA-G, the KIR expressed by decidual NK cells can only recognize these HLA class I molecules in order to avoid NK-mediated rejection of fetal tissues. We show that HLA-C recognition by decidual NK cells can be mediated by p58, () LIR-1 and indirectly by CD94r NKG2A receptors. On the other hand, HLA-G recognition is not only mediated by () LIR-1 and indirectly by CD94r NKG2A but also by a newly identified receptor termed p49. The p49 receptor, unlike the other KIR, appears to be selectively expressed by decidual NK cells.
Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoA... more Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoAb), present at the cell surface of long-term cultured T and Natural Killer (NK) cells which is involved in cell triggering. In the study described here the authors used biotin surface labelling and immunoprecipitation to show that LD6 MoAb recognizes a surface protein of approximately 65 kDa. In combination with submitogenic concentrations of phorbol esters (PMA); LD6 MoAb was able to induce accumulation of mRNA specific for GM-CSF, gamma-IFN and TNF-alpha and release of these cytokines by LD6+ T-cell lines. Both lymphokine production and lymphokine-specific mRNA accumulation induced by the LD6 MoAb were blocked totally by Cyclosporin A (CsA). To investigate the mechanism(s) of signal transduction through this activatory pathway, the authors performed Ca++ mobilization experiments. The results of these experiments suggested a role for Ca++ in signal transduction. The Ca++ mobilization induced by LD6 MoAb cross-linking could be inhibited totally by the use of pertussis toxin, indicating a possible role for G proteins in signalling through the LD6 MoAb-reactive molecule. Western blot analysis performed with an anti-phosphotyrosine antibody did not suggest that tyrosine kinase activation has a role.
Monoamine oxidase type B (MAO-B) was similarly active in the hypothalamus of 60-day-old male and ... more Monoamine oxidase type B (MAO-B) was similarly active in the hypothalamus of 60-day-old male and female Charles River rats. A single, 2 mg/kg IP injection of deprenyl, however, resulted in a significantly greater inhibition of hypothalamic MAO-B in normal males than in normal females. Repeated administration of estrogen (estradiol valerate) to intact males postnatally, a treatment which disrupts the masculinization process, although not provoking true "feminization," decreased the inhibition of MAO-B, thus abolishing the sex-specific difference. The intensity of deprenyl-provoked hypothermia and ptosis in males exceeded that of females; neonatal and postnatal estrogenization of males resulted in diminution of these effects. Androgen administration to neonate females did little affect the biochemical and in vivo parameters of MAO inhibition. It is concluded that sex-specific, biochemical differences in MAO-B inhibition may have pharmacological correlates, and both facets of MAO inhibition are sensitive to neonatal exposure to estrogen.
In this study, by the generation of a specific monoclonal antibody, we identified p75/AIRM1 (for ... more In this study, by the generation of a specific monoclonal antibody, we identified p75/AIRM1 (for adhesion inhibitory receptor molecule 1), a novel inhibitory receptor that is mostly confined to human natural killer cells. p75/AIRM1 is a 75-kD glycoprotein that, upon sodium pervanadate treatment, becomes tyrosine phosphorylated and associates to src homology 2 domain–bearing protein tyrosine phosphatase (SHP)-1. The p75/AIRM1 gene is located on human chromosome 19 and encodes a novel member of the sialoadhesin family characterized by three immunoglobulin-like extracellular domains (one NH2-terminal V-type and two C2-type) and a classical immunoreceptor tyrosine–based inhibitory motif (ITIM) in the cytoplasmic portion. The highest amino acid sequence similarity has been found with the myeloid-specific CD33 molecule and the placental CD33L1 protein. Similar to other sialoadhesin molecules, p75/AIRM1 appears to mediate sialic acid–dependent ligand recognition.
Natural Killer cells are likely to play an important role in the host defenses because they kill ... more Natural Killer cells are likely to play an important role in the host defenses because they kill virally infected or tumor cells but spare normal self-cells. The molecular mechanism that explains why NK cells do not kill indiscriminately has recently been elucidated. It is due to several specialized receptors that recognize major histocompatibility complex (MHC) class I molecules expressed on normal cells. The lack of expression of one or more HLA class I alleles leads to NK-mediated target cell lysis. Different types of receptors specific for groups of HLA-C, HLA-B, and, very recently, HLA-A alleles have been identified. While in most instances, they function as inhibitory receptors, an activatory form of the HLA-C-specific receptors has been identified in some donors. Molecular cloning of HLA-C-, HLA-B-or HLA-A-specific receptors has revealed new members of the immunoglobulin superfamily with two or three Ig-like domains, respectively, in their extracellular portion. While the inhibitory form is characterized by a long cytoplasmic tail associated with a non-polar transmembrane portion, the activatory one has a short tail asociated with a Lys-containing transmembrane portion. Thus, these human NK receptors are different from the murine Ly49, that is a type II transmembrane protein characterized by a C-type lectin domain. A subset of activated T lymphocytes expresses NK-type class I-specific receptors. These receptors exert an inhibiting activity on T cell receptor-mediated functions and may provide
Natural killer and T cells express at their surface, members of a multigenic family of killer cel... more Natural killer and T cells express at their surface, members of a multigenic family of killer cell inhibitory receptors (KIR) for major histocompatibility complex Class I molecules. KIR engagement leads to the inhibition of natural killer and T cell activation programs. We investigated here the functional reconstitution of KIR in a non-lymphoid cell type. Using stable transfection in the RBL-2H3 mast cell line, we demonstrated that (i) KIR can inhibit signals induced by Fc⑀RI␥ or CD3 polypeptides that bear immunoreceptor tyrosine-based activation motifs; (ii) two distinct immunoreceptor tyrosine-based inhibition motifs-bearing receptors, i.e. KIR and Fc␥RIIB, use distinct inhibitory pathways since KIR engagement inhibits the intracellular Ca 2؉ release from endoplasmic reticulum stores, in contrast to Fc␥RIIB, which only inhibits extracellular Ca 2؉ entry; (iii) KIR require co-ligation with an immunoreceptor tyrosine-based activation motif-dependent receptor to mediate their inhibitory function. This latter finding is central to the mechanism by which KIR selectively inhibit only the activatory receptors in close vicinity. Taken together our observations also contribute to define and extend the family of immunoreceptor tyrosinebased inhibition motif-bearing receptors involved in the negative control of cell activation.
Natural kiiler cells are part of the first line of innate immune defence against virus-infected c... more Natural kiiler cells are part of the first line of innate immune defence against virus-infected cells and cancer ceils in tiie vertebrate immune system. They arc called "naturar icillers because, uniike cytotoxic T ceils, they do not require a previous challenge and preactivation to become active. The Ly49 NK receptors are type II I rails membrane glycoproteins. structurally characterized as disiilphide-linked homodimers. They share extensive homology with t'-type lectins, and they are encoded by a multigene family that in mice maps on chromosome 6. A fine balance between inhibitory and activating signals regulates the function of NK cells, inhibitory Ly4y moiecules bind primarily MHC class 1 Iigands, whereas the Iigands for activating Ly49 molecules may include MHC class 1, but also interestingly MHC class like e moiecules expressed by viruses, as is the case for Ly49H, which binds the 111157 gene product of murine cytonicgalovirus. In this study, we review the function and X-ray crystal structure of the Ly49 NK ceM receptors hitherto determined (Ly49A. Ly49C and Ly49l). and the structural features of the Ly49/ MHC class I interaction as revealed by the X-ray crystal structures of Ly49A''H-2D'' and the recently determined Ly49C/H-2KK eywords: activating receptor, crystal structure, immunoreceptor, inhibitory receptor, Ly49, Ly49/ MHC complex, MHC class I, NK cell, NK cell receptor.
The NKp46 molecule has been proposed to play the role of triggering receptor in the natural cytot... more The NKp46 molecule has been proposed to play the role of triggering receptor in the natural cytotoxicity mediated by human NK cells. In this study we have identified the gene encoding the murine NKp46 homologue that we termed MAR-1. The MAR-1 gene is localized on chromosome 7 that is synthenic to the human chromosome 19 where the NKp46 gene is located. MAR-1 encodes a type I transmembrane glycoprotein belonging to the immunoglobulin (Ig) superfamily that, like human NKp46, is characterized by two C2-type Ig-like domains, a transmembrane portion containing a positively charged residue and a cytoplasmic tail lacking the immunoreceptor tyrosine-based activation motif (ITAM). The MAR-1 protein is expressed on the surface of cell transfectants and displays a molecular mass of approximately 46 kDa similar to that of its human counterpart. Semiquantitative RT-PCR analysis showed that MAR-1, similar to the human NKp46, is selectively expressed by NK cells. The MAR-1 protein displays 58 % identity with the human NKp46 receptor. This high homology together with the presence of a charged amino acid (Arg) in the transmembrane portion suggest that MAR-1 may associate at the cell membrane into a multimeric complex with ITAM containing polypeptides.
It is not yet clear whether immature NK (iNK) cells are bystanders to or rather participate in im... more It is not yet clear whether immature NK (iNK) cells are bystanders to or rather participate in immune responses to pathogens that may colocalize in areas of NK-cell maturation such as bone marrow or lymph nodes. Mycobacteria, including Bacillus Calmette-Guerin (BCG), have been shown to interact with peripheral NK cells and in vivo may colocalize in areas of iNK-cell development. We studied infection with BCG of human cord blood CD34 + Lin −-derived cultures containing myelomonocytes and iNK cells in vitro. Increased iNK-cell DNAM-1 expression, transient natural cytotoxicity receptor modulation, and production of IFN-γ were observed. Transcriptional receptor modulation was associated to BCG challenge, which determined increased iNK-cell cytotoxic activity against tumor cell lines and also increased killing of immature dendritic cells (iDCs). No requirement for cell contact was recorded for BCG-induced iNK-cell activation, while cytokine production including IL-18, IL-10, GM-CSF, and TGF-β contributed to the observed effects. Thus, iNK cells are affected by mycobacteria in vitro and may contribute to shaping of adaptive mature innate responses through iDC-iNK cross-talk. In addition, iNK-cell activation by BCG may represent a novel additional mechanism contributing to the effects observed upon BCG administration in vivo.
Specific combinations of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (... more Specific combinations of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (HLA) class I molecules characterized by a particular residue 80 are significantly associated with outcomes in different pathologic conditions, such as autoimmunity, pathogenic infection, cancer, and reproductive failure. Thus, a simplified method for HLA typing used in association with the analysis of KIR genotype (Kirotype) is of particular interest to extend the analysis of larger series. Here, we describe a quick and inexpensive method that allows use of pyrosequencing, a helpful subtyping of HLA class I molecules, into HLA-Bw6,-Bw4 I 80 or-Bw4 T 80 , HLA-C1, or-C2 groups and HLA-A allotypes sharing Bw4ϩ epitope or the rare HLA-B allotypes displaying the C1 motif. In particular, this analysis is focused on the amino acids around residue 80, known to be relevant in defining the affinity of KIR/HLA interaction and in the functional effects. This method was demonstrated to have good sensitivity, specificity, and reproducibility of detection and it was validated using a panel of HLA-typed International Histocompatibility Workshop (IHW) cell lines and clinical isolates. Using an allele quantitative acquisition mode, the method permitted us to obtain an accurate sequencing as required in heterozygous and/or homozygous sample definition.
International Archives of Allergy and Immunology, 1992
Drug Dosage The authors and the publisher have exerted every effort to ensure that drug selection... more Drug Dosage The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text arc in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the con stant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications and dosage and for added warnings and precautions. This is particularly impor tant when the recommended agent is a new and/or infre quently employed drug. All rights reserved. No part of this publication may be translated into other lan guages. reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying record ing. microcopying, or by any information storage and re trieval system, without permission in writing from the pub lisher or, in the case of photocopying, direct payment of a specified fee to the Copyright Clearance Center (see 'Infor mation for Readers and Subscribers').
2B4 is a surface molecule involved in activation of the natural killer (NK) cell–mediated cytotox... more 2B4 is a surface molecule involved in activation of the natural killer (NK) cell–mediated cytotoxicity. It binds a protein termed Src homology 2 domain–containing protein (SH2D1A) or signaling lymphocyte activation molecule (SLAM)-associated protein (SAP), which in turn has been proposed to function as a regulator of the 2B4-associated signal transduction pathway. In this study, we analyzed patients with X-linked lymphoproliferative disease (XLP), a severe inherited immunodeficiency characterized by critical mutations in the SH2D1A gene and by the inability to control Epstein-Barr virus (EBV) infections. We show that, in these patients, 2B4 not only fails to transduce triggering signals, but also mediates a sharp inhibition of the NK-mediated cytolysis. Other receptors involved in NK cell triggering, including CD16, NKp46, NKp44, and NKp30, displayed a normal functional capability. However, their activating function was inhibited upon engagement of 2B4 molecules. CD48, the natural l...
Proceedings of the National Academy of Sciences, 1999
Trophoblastic cells lack classical HLA class I and class II molecules but express HLA-G1. Althoug... more Trophoblastic cells lack classical HLA class I and class II molecules but express HLA-G1. Although this may prevent allorecognition by maternal T cells, it renders trophoblastic cells potentially susceptible to lysis by natural killer (NK) cells. As shown here, only a fraction of peripheral-blood NK cells in pregnant women express the HLA-G1-specific CD94/NKG2A and/or LIR-1 receptors. However, all NK cells isolated from maternal decidua during the first trimester expressed either one or both of these receptors. Perhaps more importantly, a fraction of cells expressed p49, an HLA-G1-specific inhibitory receptor, undetectable in peripheral-blood NK cells. p49 was expressed on virtually all NK cells isolated from placenta at term. Functional analyses revealed that the HLA class I-negative 221 lymphoblastoid cell line transfected with HLA-G1 was only partially protected from lysis by peripheral-blood NK cells isolated from pregnant women, whereas it was fully protected from decidual NK c...
Proceedings of the National Academy of Sciences of the United States of America, Jan 20, 2002
Previous studies showed that a subset of CD8(+) cytolytic T lymphocytes expressing HLA class I-sp... more Previous studies showed that a subset of CD8(+) cytolytic T lymphocytes expressing HLA class I-specific natural killer inhibitory receptors (iNKR) is characterized by the ability to recognize HLA-E and to mediate T cell receptor-dependent killing of different NK cell-susceptible tumor target cells. In this study, we show that this CD8(+) T cell subset can also undergo extensive proliferation in mixed lymphocyte cultures in response to allogeneic cells. Analysis of their cytolytic activity revealed a broad specificity against a panel of allogeneic phytohemagglutinin-induced blasts derived from HLA-unmatched donors. On the other hand, autologous and certain allogeneic phytohemagglutinin blasts were resistant to lysis. We used as target cells the transporter associated with antigen processing (TAP)-2(-/-) murine RMA-S cell line cotransfected with beta2-microglobulin and HLA-E*01033. On loading these cells with different HLA-E-binding peptides derived either from HLA class I leader sequ...
... We wish to thank Mrs. Cinzia Miriello and Mr. Stefano Canu for their skillful assistance in t... more ... We wish to thank Mrs. Cinzia Miriello and Mr. Stefano Canu for their skillful assistance in the preparation of the manuscript. ... 16. Moretta A, Bottino C, Pende D, Tripodi G, Tambussi G, Viale 0, Orengo AM, Barbaresi M, Merli A, Ciccone E, Moretta L. Identification of four subsets of ...
Large numbers of natural killer cells are present within the maternal decidua close to the extrav... more Large numbers of natural killer cells are present within the maternal decidua close to the extravillous trophoblast cells. Most of these natural killer cells express high levels of () inhibitory NK receptors KIR specific for HLA class I molecules. Since trophoblast cells only express HLA-C and HLA-G, the KIR expressed by decidual NK cells can only recognize these HLA class I molecules in order to avoid NK-mediated rejection of fetal tissues. We show that HLA-C recognition by decidual NK cells can be mediated by p58, () LIR-1 and indirectly by CD94r NKG2A receptors. On the other hand, HLA-G recognition is not only mediated by () LIR-1 and indirectly by CD94r NKG2A but also by a newly identified receptor termed p49. The p49 receptor, unlike the other KIR, appears to be selectively expressed by decidual NK cells.
Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoA... more Previously, the authors have described a molecule, identified by the LD6 monoclonal antibody (MoAb), present at the cell surface of long-term cultured T and Natural Killer (NK) cells which is involved in cell triggering. In the study described here the authors used biotin surface labelling and immunoprecipitation to show that LD6 MoAb recognizes a surface protein of approximately 65 kDa. In combination with submitogenic concentrations of phorbol esters (PMA); LD6 MoAb was able to induce accumulation of mRNA specific for GM-CSF, gamma-IFN and TNF-alpha and release of these cytokines by LD6+ T-cell lines. Both lymphokine production and lymphokine-specific mRNA accumulation induced by the LD6 MoAb were blocked totally by Cyclosporin A (CsA). To investigate the mechanism(s) of signal transduction through this activatory pathway, the authors performed Ca++ mobilization experiments. The results of these experiments suggested a role for Ca++ in signal transduction. The Ca++ mobilization induced by LD6 MoAb cross-linking could be inhibited totally by the use of pertussis toxin, indicating a possible role for G proteins in signalling through the LD6 MoAb-reactive molecule. Western blot analysis performed with an anti-phosphotyrosine antibody did not suggest that tyrosine kinase activation has a role.
Monoamine oxidase type B (MAO-B) was similarly active in the hypothalamus of 60-day-old male and ... more Monoamine oxidase type B (MAO-B) was similarly active in the hypothalamus of 60-day-old male and female Charles River rats. A single, 2 mg/kg IP injection of deprenyl, however, resulted in a significantly greater inhibition of hypothalamic MAO-B in normal males than in normal females. Repeated administration of estrogen (estradiol valerate) to intact males postnatally, a treatment which disrupts the masculinization process, although not provoking true "feminization," decreased the inhibition of MAO-B, thus abolishing the sex-specific difference. The intensity of deprenyl-provoked hypothermia and ptosis in males exceeded that of females; neonatal and postnatal estrogenization of males resulted in diminution of these effects. Androgen administration to neonate females did little affect the biochemical and in vivo parameters of MAO inhibition. It is concluded that sex-specific, biochemical differences in MAO-B inhibition may have pharmacological correlates, and both facets of MAO inhibition are sensitive to neonatal exposure to estrogen.
In this study, by the generation of a specific monoclonal antibody, we identified p75/AIRM1 (for ... more In this study, by the generation of a specific monoclonal antibody, we identified p75/AIRM1 (for adhesion inhibitory receptor molecule 1), a novel inhibitory receptor that is mostly confined to human natural killer cells. p75/AIRM1 is a 75-kD glycoprotein that, upon sodium pervanadate treatment, becomes tyrosine phosphorylated and associates to src homology 2 domain–bearing protein tyrosine phosphatase (SHP)-1. The p75/AIRM1 gene is located on human chromosome 19 and encodes a novel member of the sialoadhesin family characterized by three immunoglobulin-like extracellular domains (one NH2-terminal V-type and two C2-type) and a classical immunoreceptor tyrosine–based inhibitory motif (ITIM) in the cytoplasmic portion. The highest amino acid sequence similarity has been found with the myeloid-specific CD33 molecule and the placental CD33L1 protein. Similar to other sialoadhesin molecules, p75/AIRM1 appears to mediate sialic acid–dependent ligand recognition.
Natural Killer cells are likely to play an important role in the host defenses because they kill ... more Natural Killer cells are likely to play an important role in the host defenses because they kill virally infected or tumor cells but spare normal self-cells. The molecular mechanism that explains why NK cells do not kill indiscriminately has recently been elucidated. It is due to several specialized receptors that recognize major histocompatibility complex (MHC) class I molecules expressed on normal cells. The lack of expression of one or more HLA class I alleles leads to NK-mediated target cell lysis. Different types of receptors specific for groups of HLA-C, HLA-B, and, very recently, HLA-A alleles have been identified. While in most instances, they function as inhibitory receptors, an activatory form of the HLA-C-specific receptors has been identified in some donors. Molecular cloning of HLA-C-, HLA-B-or HLA-A-specific receptors has revealed new members of the immunoglobulin superfamily with two or three Ig-like domains, respectively, in their extracellular portion. While the inhibitory form is characterized by a long cytoplasmic tail associated with a non-polar transmembrane portion, the activatory one has a short tail asociated with a Lys-containing transmembrane portion. Thus, these human NK receptors are different from the murine Ly49, that is a type II transmembrane protein characterized by a C-type lectin domain. A subset of activated T lymphocytes expresses NK-type class I-specific receptors. These receptors exert an inhibiting activity on T cell receptor-mediated functions and may provide
Natural killer and T cells express at their surface, members of a multigenic family of killer cel... more Natural killer and T cells express at their surface, members of a multigenic family of killer cell inhibitory receptors (KIR) for major histocompatibility complex Class I molecules. KIR engagement leads to the inhibition of natural killer and T cell activation programs. We investigated here the functional reconstitution of KIR in a non-lymphoid cell type. Using stable transfection in the RBL-2H3 mast cell line, we demonstrated that (i) KIR can inhibit signals induced by Fc⑀RI␥ or CD3 polypeptides that bear immunoreceptor tyrosine-based activation motifs; (ii) two distinct immunoreceptor tyrosine-based inhibition motifs-bearing receptors, i.e. KIR and Fc␥RIIB, use distinct inhibitory pathways since KIR engagement inhibits the intracellular Ca 2؉ release from endoplasmic reticulum stores, in contrast to Fc␥RIIB, which only inhibits extracellular Ca 2؉ entry; (iii) KIR require co-ligation with an immunoreceptor tyrosine-based activation motif-dependent receptor to mediate their inhibitory function. This latter finding is central to the mechanism by which KIR selectively inhibit only the activatory receptors in close vicinity. Taken together our observations also contribute to define and extend the family of immunoreceptor tyrosinebased inhibition motif-bearing receptors involved in the negative control of cell activation.
Natural kiiler cells are part of the first line of innate immune defence against virus-infected c... more Natural kiiler cells are part of the first line of innate immune defence against virus-infected cells and cancer ceils in tiie vertebrate immune system. They arc called "naturar icillers because, uniike cytotoxic T ceils, they do not require a previous challenge and preactivation to become active. The Ly49 NK receptors are type II I rails membrane glycoproteins. structurally characterized as disiilphide-linked homodimers. They share extensive homology with t'-type lectins, and they are encoded by a multigene family that in mice maps on chromosome 6. A fine balance between inhibitory and activating signals regulates the function of NK cells, inhibitory Ly4y moiecules bind primarily MHC class 1 Iigands, whereas the Iigands for activating Ly49 molecules may include MHC class 1, but also interestingly MHC class like e moiecules expressed by viruses, as is the case for Ly49H, which binds the 111157 gene product of murine cytonicgalovirus. In this study, we review the function and X-ray crystal structure of the Ly49 NK ceM receptors hitherto determined (Ly49A. Ly49C and Ly49l). and the structural features of the Ly49/ MHC class I interaction as revealed by the X-ray crystal structures of Ly49A''H-2D'' and the recently determined Ly49C/H-2KK eywords: activating receptor, crystal structure, immunoreceptor, inhibitory receptor, Ly49, Ly49/ MHC complex, MHC class I, NK cell, NK cell receptor.
The NKp46 molecule has been proposed to play the role of triggering receptor in the natural cytot... more The NKp46 molecule has been proposed to play the role of triggering receptor in the natural cytotoxicity mediated by human NK cells. In this study we have identified the gene encoding the murine NKp46 homologue that we termed MAR-1. The MAR-1 gene is localized on chromosome 7 that is synthenic to the human chromosome 19 where the NKp46 gene is located. MAR-1 encodes a type I transmembrane glycoprotein belonging to the immunoglobulin (Ig) superfamily that, like human NKp46, is characterized by two C2-type Ig-like domains, a transmembrane portion containing a positively charged residue and a cytoplasmic tail lacking the immunoreceptor tyrosine-based activation motif (ITAM). The MAR-1 protein is expressed on the surface of cell transfectants and displays a molecular mass of approximately 46 kDa similar to that of its human counterpart. Semiquantitative RT-PCR analysis showed that MAR-1, similar to the human NKp46, is selectively expressed by NK cells. The MAR-1 protein displays 58 % identity with the human NKp46 receptor. This high homology together with the presence of a charged amino acid (Arg) in the transmembrane portion suggest that MAR-1 may associate at the cell membrane into a multimeric complex with ITAM containing polypeptides.
It is not yet clear whether immature NK (iNK) cells are bystanders to or rather participate in im... more It is not yet clear whether immature NK (iNK) cells are bystanders to or rather participate in immune responses to pathogens that may colocalize in areas of NK-cell maturation such as bone marrow or lymph nodes. Mycobacteria, including Bacillus Calmette-Guerin (BCG), have been shown to interact with peripheral NK cells and in vivo may colocalize in areas of iNK-cell development. We studied infection with BCG of human cord blood CD34 + Lin −-derived cultures containing myelomonocytes and iNK cells in vitro. Increased iNK-cell DNAM-1 expression, transient natural cytotoxicity receptor modulation, and production of IFN-γ were observed. Transcriptional receptor modulation was associated to BCG challenge, which determined increased iNK-cell cytotoxic activity against tumor cell lines and also increased killing of immature dendritic cells (iDCs). No requirement for cell contact was recorded for BCG-induced iNK-cell activation, while cytokine production including IL-18, IL-10, GM-CSF, and TGF-β contributed to the observed effects. Thus, iNK cells are affected by mycobacteria in vitro and may contribute to shaping of adaptive mature innate responses through iDC-iNK cross-talk. In addition, iNK-cell activation by BCG may represent a novel additional mechanism contributing to the effects observed upon BCG administration in vivo.
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